So, as I always give chance to ICS whenever newer update for it comes along, I updated today and running now on Arconium 4 (4.1.B.0.431). This is the one of the lightest ICS there is, but it is still not as smooth as Gingerbread, still I will use it for some time.
Like I said before, GB is the optimum and efficient android version for Arc/Arc S. We can only hope for an ICS that would come close to it.
32GB LT15i on Arconium 8.2 | DoomKernel v22 | V6 Supercharger U9RC11
ST25i on rooted & supercharged 6.0.B.3.184
GT-P7510 on XWLPC | A1395 on iOS 5.0.1