I'm using the B4 and B4.1 for a long time now, it's an amazing car. The design is quite old but the Asso is still in shape. This summer Associated won the world titles, in both classes.
Further to this, the Associated team drivers help us on this forum. You can find many set-ups out there and in UK you have a lot of Associated top drivers also
Sorry, but I don't have any experience on the trf201, I can only say that it's pretty much the same as a B4 carbon copy.
FYI, consider the TLR 22 buggy car also. I'm currently using this car. Tests are in progress.....
bye bye for now