and to further correct. they FAQ'd the MMR launchers (atleast for valkyries.. what i saw) while he may have been off about the turns for firing, the # of templates was rcorrect. 8 templates in 1 turn!. (it's on FW's site hp://www.forgeworld.co.uk/PDF/qanda.pdf ) they come in sets of 2, and it's 1 set per hardpoint. valkyrie has 2 hardpoints (it's become my favourate flier.. closest thing to helghast dropships 40k's got right now)
scratch all that.. i just re-re-RE-read the FAQ on it(2nd page of it). a valkyrie going into vtol to drop troops.. CAN fire in both players turns!!! and firing 8 templates per.... holy F***!! 16 templates!! granted they're only s4 ap6.. but, 16 templates!!
and it comes back in on 2+, per normal flyer rules, not reserves.
as for why hardly anyone would have one. you mentioned just the reason earlier. it's $cost. not everyone is going to have 1 (yet i plan on 2 lol but i'll swap 1HP for a set of helstrikes, for both probably, just to keep things a bit more fair) but those that do "it's worth it just for the cool factor"
Well to correct your correction of my correction. You better double check your FAQ, first, the Valkyrie can only have 1 set of Missle Pods (the Vulture does have 2 hardpoints, not the Valkyrie), thats 2 templates per pod and there are only 1 pod under each wing. And NO way any unit ever can fire in both your part of a turn and your opponents. It is confusing the way flyers work, and yes I was wrong about when it comes back into play( it is a 2+ after the first turn it arrives) The first turn it arrives is always on your opponents movement turn. After all that, you can choose to VTOL it and keep in on the board until your part of the turn. When YOUR turn arrives, you can either choose to keep it on the board thus firing it during your shooting phase, thus keeping it in VTOL through your opponents turn (making it vulnerable to your opponents fire, and read the rules, it becomes alot easier to hit, no longer needing 6's to hit) If your unit was in VTOL mode when your opponents turn started, you may NOT shoot during his turn and must wait until your turn to shoot again, however if you wish to leave VTOL, you must do it during your movement phase, thus costing you a turn of shooting. Again, does it make sense that there would be a unit out there that could do all the things you suggest and shoot in each players part of a turn. While technically the first turn you bring it into play (during your opponents movement phase) you could bring it on to the table, then activate VTOL thus keeping on the table til your part of the turn then during your part of the turn fire it as normal, but this can only really happen once unless you decide to make it leave the table again then bringing it back, but when you think about, you loose a turn of firing because it has to leave the table during your movement phase which is before your shooting phase. Your best bet is to always have it come in on your opponents turn, strafe, shoot then leave. This makes it very hard to hit (you need 6's) but there is the risk that you mau not get it back the next turn (by rolling a 1).
EDIT:
And after just reading the FAQ on the valkyrie, the part that it is talking about that you both have refered to is the exact question we are debating here, but if you notice the first sentence in the response from FW is " That is because it is not right!" they then go to explain why. Also note, that if you decide to drop troops off, you may not shoot in the turn which you drop them off. again, here is the link:
http://www.forgeworld.co.uk/PDF/qanda.pdf