Nobody has posted yet about the XXLQ2 ICS for XEU, so maybe you've all installed the German version already and everything is hunky-dory.

I got notification that LQ2 was available on Friday. I flashed it through Kies (I wouldn't normally, but couldn't be bothered to download from sammobile). Installed OK, non-wipe (yes, I do know better, but ever an optomist), set up my homescreens again. Couldn't see much change from GB.

Yesterday everthing lagged, scrolling was jerky, the keyboard wouldn't appear, and the battery was nose-diving. Ah well, as expected, it needed a reset to clear out the GB remnants. Wary of doing a hard reset in ICS, I flashed back to GB, reset, and reflashed to LQ2. Reinstalled all my apps, set up wifi, email and homescreens. But still jerky, still lagging, keyboard now appearing but randomly not responding, battery still plummeting. Next step - remove the battery. No change. Took a deep breath and wiped in ICS. No change. So, this afternoon I flashed back to LA6, in the hope of getting my beloved phone back. Reinstalled apps, set up wifi, set up home screens, etc, etc.

So, after a wasted weekend, I'm back to where I started and staying here.

You seem to have done everything you should have, so hard to understand why the problems unless the ICS firmware is faulty.
The only thing I would have done differently is to factory reset and wipe cache before and after the ICS update.
Regarding differences in Gingerbread and ICS, you have to look very carefully - bit like those 'spot the differences' pictures.

That's effectively what I did the second time around, but it didn't cure the problems. I don't think there's enough difference between gb and ics to make it worthwhile. Reading some posts on xda it sounds like I'm not alone, particularly with the battery drain. The note is such a superb phone on gb (much better than the s2 for speed and battery life) that I'll wait until the next release.