I wouldn't know about CMOS. Maybe there does need to be a constant flat-time option in ACP. But it would have to be an option, not a behavior change.

Arne and Gary Walker have done some detailed noise evaluations in high-end CMOS cameras. That's where I would start. They may already have figured this out.

If it's critical for you right now, you can always take flats in MaxIm directly. It's pretty fast, and most people don't take flats every night.