The idea in list one would have worked, if there were some smaller guys around. Because at the current state, it is clearly as follows : all the light armament (up to heavy bolter-ish) to warriors & stealers, all hwy weaponry to MC's. If there were a gazillion of gaunts in the picture, light and sometimes medium-blast weapons would target them, thus freeing firepower off the warriors or raveners. (and thus making a choice of shooting hwy weapons to them for instakills, instead of MC's)
About the issue with mycetic spores modelling: everything has a first time! Maybe you will turn out quite the modeller
Even if you do not want to work on them, you may proxy them with your marine friends drop pods or big, egglike objects
Well, nothing is perfect, especially at 1500 pts level and especially when you do not want to use small dudes. You want a relatively low amount of hard-hitting models, which will be subject to gigatons of fire at first round, effectively crippling your hitting power. Add to this the factor that only troops can score, then you are in problem as you have only two options left : stealers or warriors.
Warriors are nice, when they have cover in front of them. Warriors die faster than you can say Ilovemywarriors when they dont have this support. (venomthrope, maybe, can help with 5+ cover save and the option of going to ground under this cloud can grant you a relatively good amount of persistance. However, this means your expensive troops with deadly CC potential are having a picnic in a rain hiding under their umbrellas.
So stealers are the way to go, as they are cheaper now and still as deadly. This means you can have the numbers as in your third list, and you can have tactical options like entering from table edge or deploying in a good position when you can.
It's true that they will get shot at. So you have to make sure you act BEFORE getting shot at. This means you will either hide them very good or enter from table edge.
Consider it like this: you enemy has paid gigatons of points for deadly, high rate of attack weapons with longer range then my biggest organ, ready to spill death into the very core of your fragile but deadly troops. When you begin in reserve, you deny them their joyfull shooting. If you had began on your table edge, it is almost certain that you will get shot two turns (maybe not against orks) and your hitters will be trying to catch fast hostile vehicles and will collect all the bullets flying in the air while doing so.
It's true that when you leave everything in reserve, you also do not make use of the points that you spent for the first turn. However, you arrive in a much closer position to your enemy (which means actually speeding up) and you can shoot first AT FULL SQUAD SIZE, which rarelly happens when you opt to run towards them first. This actually makes sure that the points spent for that devourers on warriors, on trygons or fexes or zoanthropes have the chance to pay back for their cost.
When you chose to deepstrike, yes, you will get shot again but not before you do so, and you will land where you want so that you can deny most of enemy shooting, and since you hit first your losses will be relatively low as you are the one who shot first and reduced first, and most importantly, it is almost certain that you will get the charge next turn, before letting your opponent have another round of sharpshooting practice.
Its "get shot twice before doing anything else and hope to have enough troops remaining to deal the finishing blow" (which works well with crowd lists) or "let them dilly-dally then deepstrike / enter from table edge, shoot, and kill as much as you can before they deal damage back, then deal the finishing blow with whatever you have at hand. In my humble opinion, the choice is clear for no-gaunter, no gargoyler list.
about trygons: the best thing in the world that can happen to you, is that you deepstrike two trygons, (both arrive same turn and your two ravener broods do not) and the next turn your two ravener broods show up and use the holes to enter.
Unfortunately, this requires a very high amount of luck and current wording in the codex does not permit this. However, the same can be done with stealers, and with four stealer units it's possible that some of your trygons arrive before some of the stealers, and you can use the holes as your own table edge for stealers. Still not that kicky, but it may work.
About the worry that your opponent might set up: this is possible and has the potential to become an issue. However, the more he clutters together, the more he risks that your trygons will push them so that they will not have anywhere to place their models when they move out, which means instant death. The only real problem would be that their specialists units (which are rare these days) may go and grab some buildings / covers etc.
You can help reduce this problem by proper placement of terrain, if you have such a chance. what we do when we play, is to fill a quarter of the board with various terrain objects, then players place them in turns as they want but within some rules, like no terrain piece can be closer than 6" to board edge or eachother etc. So if you place your pieces (try to chose buildings) in the equador line of the field, closer to table edges, you may force your opponent to move their units close to the table edge, thus becoming easier targets for stealers. Your opponent, out of fear of stealers, may even try to stay away from them.
When your opponent bulks together in a corner, you can have multi-assaults if you arrive from that corners edge with your stealers. There are some tricky parts here. If you charge your 10 stealers into ten eldae guardians, it's quite possible that you will kill all of them and your stealers will be sitting in front of enemy models open for shooting. Instead, you should multi assault, sending about five stealer to one unit and five to another, which means they will be locked in cc in your opponents turn. If you dislike multi-assaults, I would advice running stealers in 8 man squads. You may form another squad with those other two's. This also helps you increase the chance of stealers arriving in right time in right place.
Trygons are good and will work in coherency with the rest of your army. I believe your third list is close to the best you can get. But the best list is always the one that has this small personal touch of your own, anwyay I just noticed that I have written tons of things... I hope some of them helps, and they do not cause confusion instead of clearing things out.
