Hi mate
It looks an impresive army. When I have used deverstaters, I find if I have a mix of different weapons i cannot use them all to full effect.
If your fighting an unknown enemy I use 3 x Rocket laurchers with 1 x lascannon. ( I hate saying missile lauchers as they then Miss lol.) Rocket L's are a good alrounder weapon.
For my 2nd dev sqd 3 x H bolters with a multi melta. Brill for killing infanty and light vehicles with a back up short ranged tank killer.
Other players will possible disagree but I find flamer weapons next to useless unless fighting guard or eldar. Any toughness 3 armies. For my tac sqds I like A melta or plasma guns, Rocket laurchers or lascannons. In the past I have found enermies target dev sqds and forget the tac sqds just to be killed by them on the flanks.
Scouts are good to for teleporting terminators, where you need them.
Good luck and happy gaming. M
-- Mark RG (Game on)