hmmm, thanks for the advice, it certainly got me thinking!
I think I'd better explain my motives behind choosing a
LR... I think that despite the setback of them being very expensive, I know that there are very few weapons taken on carnage games which can take down an AV14 vehicle. I for example only have 3 at best, of which one has a decent range. Plus, the Terminators are already there even if it does get destroyed... instead of quite possibly somewhere else. The terminators and transport are indeed epically expensive, but it will be very hard to shift them.
I have no personal experience behind saying this, but I have talked to some veteran carnage gamers and apparently the ideal winning armies that other people use for carnage focus more on being in the center and weathering attacks through: I guess this is because of the fact that it is easier to be there already and suffer anything thrown at you than to displace your opponents' units in time for the game end. However, what i've drawn up is a very sort of "defensive" army if you see what I mean.
I thought long and hard about a librarian actually, but the worst thing is to have your terminators retreat from the center, because then you're essentially screwed! I believe that the Fearless bonus is more valuable than psychic powers. Maybe, maybe not

ah well we'll wait and see! Esp seeing as i have a defensive army after all.
Despite the significant firepower that 15 Marines can bring to bear, relying too much on my infantry will leave me heavily out-weaponed, and again, it will be nigh impossible to shift any monoliths or the like from the center. Plus, scouts provide specialist weaponry, and I also don't "waste" points on them if you see what I mean.
It seems to me as though your mindset is geared a bit more towards versatility than is necessary in a carnage game. As one of the vets I talked to said,

"The best carnage armies are the ones that can get heavy stuff in the center,
LRs, Monoliths, Predators, Battlewagons, heavy defensive stuff. at the beginning of the game, and keep it there. heavy vehicles with heavily-armoured squads inside aren't gonna get shifted."

That's what I was trying to do, and I think from the advice I've gathered a defensive force on the table is far more valuable than an offensive force off it. However, you do have a very valid point, as if squad x is going to endure 7 turns of fire it will last a lot less than if it only endured 3, even if it is now the attacking army
I really appreciate the advice

. I'm still not entirely sure whether a more-infantry based army mobilized in light APCs will work better than one or two heavy units. I guess only time will tell, but I think I'll stick with the latter... Of the few carnage games I have played, I know for a fact either of these lists would probably win them.
I think you have a point with the librarian because unleashing Vortex of Doom on pretty much anything would be bad-ass indeed

it's a tough call, I think I'll get both and see what happens with either!
Even if I haven't changed my army list much, at the very least you've helped me think about potential issues within my list. I think I just need to see what happens!

the dice gods will decide! Worst case scenario, I'll be back here in a few months writing about my great idea for an offensive carnage army list!