Looks to me like they do exactly the same thing, wich would pretty much make them sound the same.....only difference being they make a Sustainiac for bass and the only Fernandes sustainer available is for guitar, although like I said, I met a guy who put a regular fernandes sustainer on his bass and it works, but they cant gaurantee it so they will advise against it....I really wish Fernandes would make bass sustainers and release them in the U.S.
I have to experiment with the guitar version on a bass. What I would like to have is a bass sustainer that could be installed without altering the guitar. Where is Nikola Tesla when you need him?