Really well presented investigation Slawomir, and agree the extra work for drizzle appears worth it for your set up.
Rick's posts #3 and 6 in this thread changed my thinking on drizzle:
http://www.iceinspace.com.au/forum/s...d.php?t=138224
At approx 2 arcsecs/px on my current set up, I then took the time to compare images more carefully in PI (based on some quality data from Astrofest) and realised I was almost always happy to be (quote) "trading off resolution against SNR".
An example zoomable with/without pic for my FSQ/QHY9 rig here (but not as well prepared
perhaps as your examples
):
https://goo.gl/photos/QgRWtAKxtqBFbnuM9
What I find fascinating is that the background noise often also appears more pleasing, even though you know you theoretically have less SNR (in addition to smooth stars of course). Believe that is shown in that last example.
(Dammit - Rick covered and described that better too: "Drizzle introduces correlated noise that isn't as visually intrusive.")