I have 2 and I can not say enough great things about them. Both '89, a 2555 & a 2550. I picked the 2550 up here about a month ago and have lost my mind ever since! In fact I was so blown away by the 2550 that I jumped all over a local deal on a 2555. I knew instantly that this was gonna be a main tone for me and needed a back up lol. I've owned so many damn JCM's that I had really giving up on every nailing down that tone that I hear from others. Trying every pedal that I could to dial in that tone. As soon as I fired up the 2550 I fell in love. This is how a Marshall should sound! Best Master volume taper on any Marshall that I have touched. Both the 2550 and the 2555 have a sweet spot on the volume knob just passed high noon but both sound so thick and full at a whisper of a bedroom volume. Reminds me of Diezel's low volume distortion feel. Everything is right there from the start.
Marshall really dialed these amps in. First time that I can say that both are extremely close in tone and feel. I can line up 10 JCM800's and all will sound different. I've had a few good ones and some very forgettable ones. The Jub's are very consistent. All the knobs work and are noticeable from 1-10.
To the op I'd go for it. I can't imagine the new ones would suck. I've yet to be able to compare the new vs. the old side by side but from all the clips I've heard the newer one seems a tad bit brighter.