I was in a similar situation not very long ago. I eventually decided to go with an Archer 2, mostly out of personal preference. I owned a Flyer for a while before that, and always received tremendously good communication and customer service from Tiffen. That kind of relationship is too good to walk away from. Secondly, I really enjoy the unique innovations that Tiffen provides. My first opinion of the motorized stage was that it was unnecessary, but as I started to use it, more and more I feel like I can't live without it. Same goes for the tilt head. Both tend to get a good amount of wow-factor out of people on set as well, which isn't bad.
The Tango certainly isn't for everyone; it's for a very specific market with specific shots, like dance or music videos. If you work in a market that would be sold on it, it's probably a good investment. Otherwise it isn't. I work with several directors who try to push the limits on camera movement, and tools like the Tango are very attractive to them. I don't know enough of them yet to consider owning one yet though.
If you want to check out the A2 in LA I'd be more than happy to show it off. Do research to choose, but Tiffen and Pro are both great systems.