Having dived just about every sort of dive boat you can imagine including small launches, medium launches, large launches, RIBs, fishing boats of all shapes & sizes, catamarans, sail boats, live-aboards, saveiros (large wooden sail boat), 5000 ton survey vessels, even including a 300 ton small freighter which we had at our disposition in PNG while waiting for a cargo to arrive, I'd say that as long as it floats and has an O2 bottle the rest is just trimmings. If it doesn't have an O2 bottle go and rent one somewhere.
The only boats I don't like diving are those small metal ones (aluminium sheet construction) because it's a real pain getting back in after the dive without capsizing them.
If the crew is experienced then great, if not just make sure you brief them well as to what is expected of them in a few basic scenarios. I've dived off many boats that knew nothing about diving but once we explained the routine and the requirements there were no problems. It ain't rocket science, it's basic common sense which most sailors learn very quickly.
There is one thing though that really endears me to a boat - a generously sized, firmly fixed, strong ladder which extends well down into the water and well up above the platform and which I can climb, fully kitted without assistance even in rough seas.