Harvey, if you have the money, now (I think) is the time to buy TG2. The biggest reasons I can think of are:
1. It's inexpensive now, since it is is still a preview. The price will go up, once it goes live.
2. The developers, testers, and brilliant community are here now to help us all learn about its intricacies as well as help us with fundamentals.
3. This is, more or less, on the ground level of the program, which is a great privilege.