I just installed RegiStax5 and decided to see what improvements I could get vs. version 4. Here are two examples from my first couple of days of dinking around. In each pair, the left image is my best effort using version 4 back in November 08. On the right is the same region processed from the same avi. using version 5. In both pairs I think you can see some significant improvement around Tycho in terms of the surface texture. The first image is a crop of the full frame at prime focus. The second image is a crop of the same region using a 2x barlow. In both cases the scope was a 5" Mak-Cas.
Both of the reprocessed pics were done with a reference frame (limited to 50 and touched up with wavelets). I also used the "estimate alignment points with 64x64 boxes and a spaceing of at least 75).
I think the results show that version 5 does offer some improvements over 4. Not only did I get more surface texture I also could process the full 450 frame avi files without it choking. I was using a StarShoot SSCI II (1/2" chip) so each avi was about 1.4 Gb.