Back in the freelance game music days when it seemed money fell from the sky is when I got my 90HAM.. I very seriously considered a 555 given that I was (and mostly still am) a novice guitar player.
But since my quest for a 77GMC I've been reading voraciously on Jemsite and Universal Jems about these guitars, and took a trip to Guitar Center, and realize that there's quite a noticeable difference when playing, even for a novice, between a Lo TRS and a Lo Pro.
Nevertheless, imo you've got a great guitar to start with and I think the 555s are a good way to introduce someone to a Jem, since honestly finding a used 7 or 777 is tough to do under 1k. Once you consider yourself a pretty good player, trade up and you'll be pleasantly surprised at how your skills meld with a standard Jem.