Used to have one, but I dropped Randall when the 3rd amp in 2 month's time malfunctioned (first two T2s just went up in smoke and then that one RM100 began to feedback like crazy even though I had an ISP Decimator hooked up).
Now moved on to ENGL and couldn't be more satisfied with it.
Not sure about the build quality on Randalls :D,
but on the rare occasions they worked they really delivered tone.
Mine had a Blackface, an UltraXL and a modded Ultra module.
Great clean, really beefy high-gain rhythms and top-notch leads.
Maybe I was just out of luck (three times in a row... yeah right),
but RM100s are really capable of some good tones IF they work properly,
as well as some great features like the Bias section in the back.