I looked at Avernum today. I think they're very neat. Both sacred troops are recruitable out of the box, and I love the "full hitpoint" regen that the one guys have. I was thinking of a high earth and water bless, maybe even air. I haven't had time to give them a chance.
They also have a huge variety of magic which excites me
I don't think the crystal people losing their astral pearl free spawn makes them terrible. I'm not sure exactly what I'd do with them, but making them mind hunting machine seems like a good idea. Maybe if their cost was lowered they could make good research machines with the low upkeep cost from the sacred status.
Jazzpei