Even ATR is beginning to admit that Hotel Mode isn't very good. They've implemented in their -600 variant an electrothermal air conditioning unit to "supplement" hotel mode bleed powered cabin cooling. (Talk about adding weight!) You've gotta love how they spin this correction for lack of original performance as a wonderful enhancement LOL
(Engineer's rule #2: If you can't fix it, call it a feature)
The APU on the Q series is much better than hotel mode, and DOES operate unattended. (unlike some APUs and Hotel mode).
ATR also put the hotel mode on the same side as the service entrance and fuel fill port. so no servicing can be done. So much for turnaround time at the gate.
Sure, they cal Hotel time "ZERO ENGINE" time ...but the prop brake fails pretty often. (under 3000 hrs mtbf). I am pretty sure APUs last longer than THAT!