Clandestino, I can indeed confirm that the Dash8 loos can be used on the ground with APU or GPU on - that's usually where the CPT can be found on turnaround...
The Dash, while it has excellent performance (very close to some RJs), still has reliability issues - they do go tech quite often. While I don't work on ATRs, those that I see on turnarounds here don't ever seem to go tech (but I'm sure it must happen every now and then).
The Dash8Q-400, as has been said, can be quite tricky to trim properly with the tail compartment empty and/or a light PAX load (even using compartment 5 by the front galley), so sometimes we may have to put on ballast.
Cheers
