Now this is just my opinion.
I have stopped making any of the Sierra and clones. I've switched over to the Elegant Beauty (from Aaron)/Aero (from CSUSA). The design of the kit it better in terms of transmission placement (in the finial instead of in the middle). It is very tube length sensitive but I don't see this as a big problem.
The problem that I and others have had with the Sierra's is people will lose the tranny in the top of the pen and send it back. Yes it's retrievable, but a pain to deal with. The EB/Aero (also the Squire and Art Deco from PSI) doesn't have this problem. If they move the tranmission on the Sierra's I might come back.