I've started another Insane run pure 1.2 canon story, after finishing the previous one, started on 1.1 with imported save and patched to 1.2 half way there.

I'm seriously under the impression that difficulty has been reduced, at least up to Act 1 where I am right now. I can't have improved that much. Endregas and Nekkers are dying so fast that it is really a surprise.

And this with all mods I used removed. (extended pots/oil duration, reduced crafting items weight, extra load limit for Geralt) So most of the time, potions and oils wears off real fast and it doesn't make the slightest difference!

Does anyone else have the same perception?

Patch 1.2 included come balancing in the Prologue. The patch notes are available at http://www.en.thewitcher.com/patch1-2/ in case you wish to see the entire list of changes, fixes, etc.

Oh, I know that. I went thru the changelog on the eve of the patch release, as it was announced by the guys at the E3 live feed. But I am not talking about the Prologue. It's past that. Aw well, perhaps I am getting that good with the game, given it's my 6th playthrough, 4th insane run (2 successful!) and I know what works best on which foe.

I am not complaining, just stating an impression. Perhaps it is just that. (but I'd hate if it were indeed nerfed to accomodate those whiners that cry "too hard" instead of learning how to beat the game!)

It does seem quite likely that you're simply getting good at critical mechanics like controlling the camera and maintaining good tactical awareness, knowing how the enemies tend to act, and timing those wackily common rolls.

Some nerfs definitely carry over from the prologue - such as being able to hit multiple enemies in front of you without whirl.
Definitely feels less difficult for me as well, although I am not quite able to pinpoint it on a specific "feature" except the one above.