Not bad! I play gunline guard (with a sprinkle of mech) so a couple of minor suggestions...
I like the inclusion of a lascannon in the Co Command Squad. Good use of the higher BS. Flamers... not quite as much. I'd recommend skipping the special weapons altogether, but if you must have one, I personally like grenade launchers.
Ministorum priest - who'll you be attaching him to? Whoever he goes with, I'd recommend dropping any heavy weapons in that squad.
Platoon Command Squad gives you access to some miscellaneous and sometimes useful extras, such as sniper rifles. I like to run my PCS's with 4 sniper rifles or 4 grenade launchers. Just a bit of extra firepower for a small points cost, and from time to time it actually makes that PCS useful.
Infantry squads, I like to give them either flamer / grenade launcher and an autocannon. Grenade launcher is a great go-to weapon, better than people usually rate it (though not spectacular). Flamer is awesome for objective grabbing / holding (don't underestimate overwatch). Melta's short range tends to work against it. You might find that you'll rarely get the opportunity to use it in a useful capacity. Autocannon is a happy option, very well-liked among guard players. It'll murder light infantry and chop up transports without too much difficulty, and very cheap as well. Lascannon, not many guard players like, but I personally fine it useful in a gunline.
Leman Russes - thanks to the new ordnance rules, when you fire your battlecannon, you can only fire other weapons as snap-shots. Therefore I recommend removing the HK missile and lascannon. Just go with a barebones LRBT, no sponsons up upgrades at all.
Special weapons squad, I have no issue with. Possibly buy a Chimera for an infantry squad, then mount the special weapon squad in it instead? That'd make them half decent for objective grabbing.
- April's Featured Fiction winner!
A World Eater survives another day at the office (barely).