I own a rocktron utopia b100(which is a little similar to the the rocktron utopia b300). if you're wondering how the rocktron processors sounds, I have sound samples of the rocktron utopia b100 on my soundclick website. here's the link.
www.soundclick.com/crystalman85
From what I can tell you, rocktron processors are a little different from the boss gt-10b. the distortion channels are a little rough and metallic sounding. but the modulation effects sounds awesome. I dig the chorus effect. it sounds smooth and lushful. if you prefer more variety of effects, go with the boss gt-10b.