Pretty sure 4.1 was free. My Tassman 4 serial number email is from July 2004.
The forum appears to be gone. I have not looked for it in some time.

IIRC, I had Tassman V3 that came with one SONAR or another.  It was very cool, but finicky.  I wanted to really love it, but I guess I didn't because I never did upgrade.

Tassman sure makes some great sounds, but the UI could certainly use some love and is the main reason I don't use it more often tbh. It's hard to look at when comparing it against more modern synths and  there is no way I would ever have bought it at full RRP for that reason alone. I got it as part of the modelling collection bundle when that was in no brainer territory sale a few years back, so it was practically free seeing as I was going to buy a couple of the others indivdually anyway.  There hasn't been a forum for years that I have seen, but the customer service is absolutely top notch in my experience, so not really the issue that it could be with other vendors who are maybe not so forthcoming once they have your money.
 
I was told some time ago that a "new" Tassman was being looked into, but that apparently it isn't an easy job even to just give it a UI makeover because of the common architecture they have moved to with the other synths. If they did it though I'd be all over it if the upgrade price was sensible.
 

They've been talking about updating it for like a decade, and I'm not kidding.
 
So I would suggest only considering it as a finished product, with perhaps a few maintenance fixes now and then, and don't hold your breath for a version 5 update until you see tangible evidence of it.

Another Tassman owner here. I say "owner" because I never use it as I couldn't be bothered getting my head around it, and I hated the GUI.
 
A|A|S do some great stuff and I have, and use other modelling instruments of theirs.
 
Since invested in Reaktor and that is a lot easier to use, IMO, especially with "Blocks."
 
Their forum has been quiet for so long that I stopped bothering to visit it. However, I have found the guys very helpful when e-mailed and reply, if not within a day, certainly within two.
 
 

oops... hit reply twice for some reason... sorry

I have it.  It makes great sounds, but it is clumsy (to me) to create a new synth.  Then again, until Reaktor came out with Blocks, I found that difficult as well.  
 
I think AAS really excels at real-world modelling.  I love string studio.  And their electric piano thingy is great too.  VA is easy to use, but there are so many competitors on that front.  

oops - an echo (echo echo) in here.  

I got it by upgrading to the modelling collection bundle a while back but I have yet to do much with it.

I love Soft tube's modular for straightforward but versatile modular programming, Its (almost) only monophonic. I hope if I ever get round to Tasman will give me some of that with polyphony.

drewfx1
They've been talking about updating it for like a decade, and I'm not kidding.

Yeah, but I do believe them when they say an update is coming.  I talked to one of the AAS principals a NAMM 18 months (or so) ago, and he said that Tassman 5 was in the pipeline but that several things were ahead of it priority-wise.  This has to be a most challenging set of problems to solve.  AAS has been converting all their instruments to a new architecture over the last five years (or so) and Tassman is the last hold-out.  Clearly it's the most intricate instrument in the AAS catalog.
 
I have not played around with Reaktor blocks at all, but from my uneducated position, they appear to do something very similar to Tassman.  However, it's my understanding that Reaktor blocks are monophonic.  I'm pretty sure Tassman is polyphonic (it's been quite a while since I checked it out).  Anyway, my point is, if and when AAS finally delivers, it could be something pretty special.