That's interesting. I just tried out some Sterling JP models the other day.
I bought a Music Man Luke III last year and fell in love with Music Man guitars -- they are so well made. Recently I've also been wanting a Music Man Petrucci guitar, but I can't afford it, as I'm still paying off my Luke.
So I took a look at the budget Music Man's and tried out the JP100D and the JP60 Sterling models last week at my local guitar store. I'm guessing that's similar to the PRB models you mentioned. I'm in the US so that's what they are called here. Anyway I thought they sounded and played pretty good. I like the neck profile, which is similar to my Ibanez guitars. You can play fast on them -- sweep picking licks are easy on them -- and I liked the fact it had locking tuners -- something you don't see that often on budget guitars. Locking tuners make so NICE when changing strings, and give more string stability. The tremelo bar stayed in tune pretty well, although I don't go that crazy with whammy bars.
The pickups on the JP100D have Petrucci's signature DiMarzio pickups -- the Crunch Lab and LiquiFire -- so it costs more and it sounded good, but I actually thought the cheaper JP60 model sounded pretty nice, too, with it's non-signature Dimarzio pickups. I'm not that big of a Dream Theater fan (but I do dig Petrucci's playing) so I don't think that I need to get his exact pickups. The JP60 pickups sounded fine to me, and I might do a pick up swap later down the road. Maybe put in DiMarzio Transition pickup (got it on my Luke III) or see if my Seymour Duncan JB pickup would fit. But I think I'd be happy with the stock JP60 pickups, too.
The JP100D and JP60 don't have all the piezo features and other extra stuff from the Music Man JPs, so that can be a negative, but at it's price point, I thought the Sterlings were pretty nice.
I also tried out Petrucci's new Majesty Music Man model, and man that is a fantastic guitar-- futuristic body and so lightweight. You can get so many different sounds from it with all the switches and piezo combos but it's crazy expense. I wasn't quite convinced it worth getting at that price (around $2700 to $3000 in US dollars).
That expensive price point of the Majesty just made the Sterling JP models look more enticing to me.
The store also had a used Godin, too. Don't recall the model. I picked it up and I didn't plug it in. I just tried it for a couple minutes. The neck just didn't feel right to me, after playing the JP Sterling guitars so I put it back on wall. The neck profile was much thicker. I do like thick necks too, as I own Gibson Les Paul, so if I was looking for a different type of guitar, I would have tried the Godin more but I was in the market for a fast-playing guitar, so the JP Sterling mdel's thinner neck felt better to me for that. I also looked at some nice ESPs and Prestige Ibanez guitars which some nice fast necks, too, but I ended playing the JP Sterling the most in the store. It could that I already own Ibanez guitar so I want something different.
Anyway, I'd vote for the JP Sterling model. If you don't need Petrucci's signature pickups, just get the cheaper JP60 model. It's the same guitar as the JP100D from what I recall reading online. Oh yeah, I thought the paint jobs on the Sterlings were nice. It impressed me. The JP60 had this cool blue burst paint job and the JP100D had a natural Koa cap (really nice!). I think these are brand new models/paint jobs.
Hope that helps.