Nice images Colin, remember you can capture Jupiter for 3 minutes and Saturn for 5 minutes without any problems with rotational smearing. AS!3 does a great job in aligning the pixels that might be shifted slightly, even on my alt/az scope that also adds field rotation.
For instance, I capture around 27000 frames for Jupiter (180sec x 150fps) and 30000 for Saturn (300sec x 100fps) and stack about 5000 of each for the final image.
I always use 3x drizzle in AS!3, just to make the images bigger so I can see the effects of sharpening and noise reduction easier - if you can get them to look good at 3x captured size, they always look a lot better when reduced down to captured size
.
Finding good settings in Registax is the part I have the most difficulty with. Nowadays, once I find a good setting, I save it and use again as a start point for the next session.
Andrew