For the love of doughnuts, fix Lumbering Behemoth!
If you allow LR's to be taken as Troops, you more or less invalidate the Core formation from Mont'Ka. Even then, you're making 5 Russes as the minimum for a CAD, if you reduce the TC's unit to a minimum of 1. Realistically, that should be at least 6 Russes. With some upgraded gear, that's a minimum of 960 points.
Not that GW cares about that, of course, but unless you're playing 2000 points or more, there isn't much wiggle room at 1500 points.
First order of business needs to be fixing Guard's mobility options. I recently played an army list in which I took...
Guard CAD
CCS, 2x Vets - Lots of Plasma, in the Allied Pods
Marine CAD
Techmarine, 2x 5 Scouts with Camo+Sniper, 3x Dreads in Pods, 3x Empty Pods
Guard Artillery Formation
CCS, 2x Bassie, 1x Manticore
I went up against my buddy's Eldar, and narrowly won the Relic. I haven't played an IG army even close to that effectiveness. The Pods and Dread support were amazing, while the scouts stole the relic and ran back to the Arty.
Point is, that without the Pods, and some Melee deterrent, I would have been unable, in any way, to capture the objective. Guard need mobility at a reasonable price. Russ are mostly irrelevant in light of Gauss, Haywire, and widespread Krak grenades on mobile platforms.
Russes aren't really the problem. They need Lumbering Behemoth fixed, and their rear armour upgraded to 12 for all varieties.