I've heard the aliens get a bit shorter sessions. I'd imagine it's because of the shallowness.
Yep. It's actually the big reason I have a problem with them. With a deeper bowl, the top can get dried out, but the lower sections that are heating up with boil juices up to keep that top layer moist for much longer. With the alien, that doesn't happen much. That's a big part of why that bowl smokes so much better when it's overpacked.
This is my experience exactly. That's why I've been smoking from my Harmony exclusively for a while now. Three sets of coals and I call it done.