Sorry for posting on something non-FOSS but there has been enough talk on Bitwig over the years and that piece of software costs five times as much for me to not feel guilty...

Anyway I noticed Renoise has brought out Redux fairly recently. Thought I may have seen some chatter about it already as there is at least one Renoise user on the list and sure some of you used trackers back in their hayday.

Unfortunately Linux VST only but still maybe of interest to some of you...

http://www.renoise.com/products/redux