I have always tried with my 3 armies to make troops the backbone of the force. Though, I do not do the 50% rule (generally, I use about 40% in troops in an army). The reason I do that is mainly fluff reason. Most armies main contingent is the standard space marine, guardsmen, fire warrior, what have you and only very rarely do you see a specialized force (Bel'taan eldar, Deathwing, and few others). Soap Box aside, looking at your list, I would definately drop the bikers for a raptor squad (mobility is really good on them) and use the remaining points for some more troops (lesser daemons if you are locked into that rought). Chosen are great for their point cost. Weapon options are outstanding and infiltrate is even better. I would drop the possesed for another squad of chosen, give both chosen an icon, and (again) put the remaining points into troops. This will give you 2 infiltrating units and a jump pack unit to drop off some daemons. Some other suggestions I have is; if you go with raptors, give your sorc wings to run with them. This tends to be a very mean unit (specially if you give the raptors an Asp. Champ. with lightning claws). Lasty, choose your weapon options carefully. Chaos, unlike their estranged brothers (space marines), get the use of autocannons. They are as good as a heavy bolter squad but can take down light armored tanks just as well (something heavy bolters can not do effectively). Along with this, your chosen has some weird weapon combo's. Mixing melta and plasma is never a great idea (as on is rapid fire and the other is assault). Figure out what you want the chosen to do and equip them that way. If you want them to do a dauntless stand and shoot, use plasma guns. If you want them to do move and shoot, use melta guns. And, If you want them to be assault monsters look into power weapons, lightning claws, and Power fists. With infiltration, the sky is the limit with these guys. Hope I helped.