There are no instant deaths besides the drill and the flying moments. Oh, that reminds me, I also died once in that area where you have to be stealthy. I missed the hydraulic spike things with my stasis, went to stasis again, had no packs, and died.
The hardest part for me was that stupid climbing segment with the falling walls, just because the gap jumping wasn't always 100%. Everything else was easy though. I honestly think Classic mode was the most difficult just because of the loss of crafting and attachments.