Hi Michael,
I am/was the main developer of Aldrin. Aldrin is currently in a "dormant" state, that is, it has been largely abandoned. I have ceased to work on it since about two years because of private affairs (new wife, moved to Hamburg), but I still used Aldrin since then.
Pieter Holtzhausen and others took over maintenance while I was away, but apparently there was little interest in keeping Aldrin going, maybe because of the awkward project structure, or maybe because we have a user community of just about 3 people

Bucket Brigade forked Aldrin and continued working on it, but his product appears to be as buggy as ours:
http://sites.google.com/site/neilsequencer/newsAfter thinking long and hard about what bugs me about Aldrin, I decided to write Aldrin's unique components from scratch, as part of the larger Jack Audio Connection Kit infrastructure on Linux. So the spiritual successor of Aldrin is going to be "Jacker" (Jack-Tracker), which is a pure sample precise MIDI tracker/sequencer for the JACK bus. It's going to be usable in about 2-3 weeks.
I hope that answers your questions.