Hello. New guy to the forum. I've been using a 615 for years and I am thinking about upgrading to a 655 for the Gig lan. There are a lot of rev A and B available secondhand. Rev C cannot be found but I read that C is a modified B1. I am reading PROs and CONs of rev A and B and it seems like more people prefer rev A. If true, which rev A ... A1, A2, A3, A4? Thank you.