Ok I'm going to take an objective and frank look at this.
Guardsmen Bob wrote: HQ: Company Command Squad (Vox Caster + Grenade Launcher x1)
1 Master of Ordnance,
1 Chimera, Multi-Laser + Heavy Flamer
Firstly you have 4 BS4 models that you're required to take. Why are they holding lasguns, a grenade launcher and a Vox? Take advantage of their shooting prowess and give them weapons. Plasma is great in this edition, so is melta. I'll explain why grenade launchers and voxes are a no go in the summary Elite: Psyker Battle Squad (6#, 115 pts) *Divination*
4 Psyker Battle Squad,
1 Overseer,
1 Chimera, Multi-Laser + Heavy Flamer
I don't know where you saw that you can take divination for anything in the guard codex, because you can't. PBSs can't even swap out their powers. You also have the problem of not being able to use any of hte PBS powers from a chimera. Ditch these guys and don't look back until the next guard codex, when they become a usable unit again. Heavy Support: 1 Leman Russ Battle Tank,
Heavy Support: 1 Leman Russ Battle Tank,
Heavy Support: 1 Leman Russ Battle Tank,
You're serious lack of AP3/2 everywhere else makes these an OK choice. However LRBTs are pretty poor. 150pts for a 50% chance to hit. They are worse at killing everything than the Exterminator, except for MEQ standing in the open, or in 5+ cover. 3 of these mediocre tanks doesn't really cut it. Troops: Infantry Platoon (25#, 145 pts)
1 Infantry Platoon, *Combined*
4 Platoon Command Squad,
1 Platoon Commander,
9 Infantry Squad, (Grenade Launcher x1)
1 Sergeant,
9 Infantry Squad, (Vox Caster + Grenade Launcher x1)
1 Sergeant,
What's the vox for? Why do you need to reroll orders on a squad with lasguns and a single GL Troops: Infantry Platoon (25#, 145 pts)
1 Infantry Platoon, *Combined*
4 Platoon Command Squad,
1 Platoon Commander,
9 Infantry Squad, (Grenade Launcher x1)
1 Sergeant,
9 Infantry Squad, (Vox Caster + Grenade Launcher x1)
1 Sergeant,
As above
The serious issues I see are:
1) There's no threat here. I look at your list and I see lasguns. There's nothing here that will damage anything. Transports are safe,
MEQ are safe, hell, even guard are safe, since the only thing you have >36" range is three, one shot blast markers which are horribly inefficient. Range and threat are important. If you face another gunline, you'll be out-gunned fast. Your opponent only needs to hug cover and let you fire the 3 >36" shots while they use their long range weapons to pick off anything you move forward to get in range.
Grenade Launchers are a trap weapon. Never, ever take them.
Str:6
ap:4 doesn't make them the jack of all trades they seem to be, it makes them
terrible at everything. A plasma gun will beat a
GL at killing everything and anything. Yes it costs three times as much, and has a chance to kill the user, but it is more than 3 times as effective at literally everything, especially when you take into account rapid fire. Similarly, a
GL firing the blast (considering you'll hit around 2 models) is as powerful as a lasgun at 12". With FRSRF the
GL using frag rounds is weaker than a lasgun. Kinda crappy for a 5pt "upgrade".
A vox is only useful when you
need an order to get through. The only thing that needs an order to get through is a
HWT. Even then it's not worth it. For the cost of your Vox network, you could have more upgrades, to make your shooting fare more effective.
The lack of threat also means 2+ saves will walk all over you. If you do manage to pour enough fire into 2+ saves to kill them (which is possible with many lasgun shots) you will not have touched anything else bearing down on you.
2) No anti-tank. How do you intend to deal with tanks? The
LRBT is
terrible at destroying tanks. This is yet another trap the guard codex puts out.
Str:8 is a mid range shot for
AT, and with rerolling armor pen, it seems decent. However the ap3 means that even if you do manage to penetrate
av:13 or 14 (which is rare) you still need to roll a 6 to make that shot count. It's very hard to kill vehicles with battle cannons.
Now consider that your opponent has both
AV:13+ and foot soldiers. How can you handle both? Your lasguns and
GLs are relying on luck to kill anything, and so your battle cannons will have to work on both tanks (which they're horribly inefficient at) and infantry (again, which they're horribly inefficient at).
Melta-guns and lascannons are the best way to deal with tanks.
3) Empty weapon slots. Guard are about special weapons. Lasguns are not important until your opponent is in your face. You have 7 heavy weapon slots empty. 7! That's 7 lascannons, or 4 lascannons and 3 autocannons. That's where the damage comes from. Not from lasguns.
You don't have to decide to blob your infantry in the list making process. Let that be optional. Generally multiple squads are better as you have more targets to shoot at, and more targets to be shot at. Also, on a rules note: The
PCS can't be blobed in with the PISs. I'm not sure if you intended that but that's how it reads.
far too many points and still painting...
Eldar, 
Lamentors, 
Pre-Heresy EC, 
CSM EC, and 