The MU100R and MU100 are the exact same in terms of sound. The MU100R is twice as long and came with the PLG100VL and PLG100VH installed from the factory and is all jet black instead of a dark gray color.
Voice patches in this demo: Double Concert Grand Piano Hard Picked Bass Resonant Double Hammer Guitar 6th Hit Meditation JJJ Rogue Kit Tramp Kit/Coffin Kit Brush Kit 2 Vexation/Divinity Fuss Curse Lead/Toad/Manhattan Bridge DX Bass Rage Xe + Malfunction Random Run Diploid 1 Click Gospel Organ Stereo Slow Strings Small Latin Kit (SFX)