As black I reached this position in a recent game
[White "Somebody"] [Black "Ian Bush"] [Result "*"] [ECO "B07"] [FEN ""] [StartPly "23"] 1.e4 d6 2.d4 Nf6 3.Nc3 g6 4.Be3 c6 5.f3 b5 6.a3 Nbd7 7.Bd3 Bb7 8.Nge2 Qc7 9.Ng3 Bg7 10.Nce2 e5 11.O-O O-O 12.dxe5 dxe5 ( 12...Nxe5 )
On running it through the Lichess analysis it reported 12 ... dxe5 as a blunder. This, to say the least, somewhat surprised me, but on sticking it through Stockfish on my own machine the semiconducting monster does indeed markedly prefer Nxe5 - taking with the Knight it puts at ~-0.4 and taking with the pawn +0.25, so over half a pawn swing. I preferred taking with the pawn to avoid having a potential weakness on d6, and also thought his pawn on e4 so well defended that the half open e file was little use to me, so I am struggling to understand why 12 ... Nxe5 is so much better. Can somebody enlighten me? Is it simply to get the white squared bishop for the knight, or is there a deeper strategical meaning? I do understand that taking with the pawn is more unbalancing, and so what I would definitely prefer if needing a win, but I just can't see why it is intrinsically so much better.
More generally this kind of decision is not uncommon in the Pirc and some related openings, are there any general pointers as to which should be preferred?