I find 6 hard because there are so many instant kills and it's easy to get surrounded and die quickly. The enemies are weak, but it's hard to survive if you're completely surrounded because they're so fast you barely have time to shoot or melee. The other day I was at full health, was knocked down by a guy, then there was a whole group hitting me with their weapons, I kept getting knocked down and couldn't even heal because right when I was about to, I'd get hit again. I couldn't run or dodge, they were all in the way, so I died when not even thirty seconds before I was at full health and I still had fifteen herbs and a first aid spray. And it didn't help that Jake was standing there just watching. xD
That's just my experience though. Maybe the game and enemies just like you more.
I only remember one insta-kill and I just rebeat the game recently. It was those ear-wig looking guys that pick you up and bite you in half. As with every Resident Evil game... use the shotgun and you're pretty much untouchable. Resident Evil 4 had far more insta-kills imo... Salazar's is ridiculous if you don't time it right.
Maybe they do like me more xD There is just too much ammo and I find there is an answer for everything. The game just hands you everything on a silver platter and you're overloaded with ammo that you're dropping it to clear your inventory for herbs consistently.