Might be a lot of wasted energy...
I've never shot LBT's @ 2000+ f/s, so I really don't have the foggiest idea of how they'll behave, but considering how much critter they'll penetrate at 1200 f/s, I think the big difference may be how much dirt they'll penetrate on the other side of the critter.
Two seasons ago I took a buck with a 335 WLNGC fired from my Ruger Bisley (m.v. was in the 1280's). The shot was at a little less than 50 yds and the hit was a solid double-lunger which creased the top of the heart. While he was as good as dead, he did last for a few minutes and managed to go about 100 yds after the hit. While the bullet performed as intended (complete penetration in a straight line), an expanding design would have probably resulted in a quicker kill.
I think the LBT's are excellent for bear defense with a revolver as penetration is essential. I also think they have some utility as hunting projectiles for the tougher species (elk. large hogs, etc.) if one is using a firearm with an insufficient level of energy to ensure adequate penetration from all angles with an expanding bullet.
Considering the energy level of a smokeless ml'er, I'd probably lean more towards a tough expanding bullet (like maybe a Barnes X) which would have plenty of penetration and a larger wound channel.
All that said, an LBT WILL punch a hole wherever you place it.
