I've always found the standard Leman Russ to be an adequate weapon for 2000 point games. A lot of people I know don't even bother with the sponsons (although I'm a fan of them) because you're bringing the thing for its battle cannon. Occasionally, you get more of an effect by firing massed "little guns" though, so having a hull heavy bolter, heavy bolter sponsons, and a pintle heavy stubber make the vehicle suitably deadly in that regard.
The Demolisher, oddly enough, is more of an all-rounder. The standard Leman Russ, at its core, is an anti-infantry vehicle due to how blasts work against armour. You pretty much need to get a hit on the scatter die to cause any reliable damage to an armored target--even an APC-- with a battle cannon, but you can really jack up an elite infantry unit with one. The Demolisher packs a more powerful main gun, so even if you do miss the APCs, the halved strength can still usually do something, albeit on a 5 or a 6. On the two dice you get though, odds are pretty good that you'll get one. That fact alone makes the Demolisher more adept at anti-vehicle operations, although not significantly. Putting a lascannon on the hull isn't bad, particularly if you have the plasma sponsons (which, to be fair, you might as well take, because it's the only way you can get those guns in the army, and they're awesome.) and can fire all three at a target.
A forum community dedicated to Warhammer, Warhammer 40K enthusiasts. Come join the discussion about Warhammer and Wargaming collections, miniatures, tactics, terrain, reviews, accessories, history, displays, models, styles, scales, reviews, accessories, classifieds, and more!