I love Tassman 4, I'd have liked to see what they did with V5, but I imagine it is not their top seller, and the announcement suggests that the code base has become difficult to manage. Pity!
I've owned it since it was an add-on for Sonar, and cross-grade almost immediately to the full version. It was a remarkable tool, but it was also a resource hog, and it kind of fell by the wayside for a bit. I can't remember exactly which version broke the resource barrier (I think it was 3?) but once it became usable I returned it to its proper place in my plugin menus<G>! It remains part of my template, and about the only reason I can think of to ditch it would be when it stops working - or when AAS introduces a replacement that is worthy.
Don't get me wrong, I use Ultra-Analog and String Studio, and I think their current versions were well thought out improvements on the originals. But nothing quite sounds like Tassman. I hope it works for a long time!
20 years???