Hi Greg,
Your new telescope sounds like a lot of fun, and being so fast it makes imaging much more...dynamic
Yes, max ADU values are somehow lower with QSI cameras that have Sony sensors. Mine goes up to 64000, while QSI6120 goes to 49000 - that's at least what I have read on the forums.
Thank you Ray - and you might be right regarding uneven cooling. Whatever the reason, there is a very slight gradient in my bias frames, but 10-minute darks show different pattern - there are three brighter areas near the edges of the CCD. These do not show up with shorter subs. Reinstating, these variations in ADU values for bias and dark frames are in my opinion negligible and do not affect images at all.