I have the Rhino 3000 as well. It certainly has it's up sides: very wide variety of tapes/heatshrink, battery powered, somewhat rugged, and widespread support.
However I'm still in the air about it. For the price you pay, it should be able to do a *lot* more. For instance you can't set the character spacing. You can't add any type of bordering to the labels. The label cartridges seems ungodly expensive, and you waste a lot of 'test' labels. The output print size will never seems to be what you expect; it's just all very quirky. Certainly don't buy this as your one-and-only, 'general purpose' labeler, as it is not. Maybe that was the mistake I made. Take off the rubber case and it has a cheap feel to it.
Oh and to the poster about the labels not centering: I had this problem too, until I realized I wasn't seating the cartridges fully. I cringe every time I put one in, because it make a loud, plastic-on-plastic SNAP.
Anyway, sorry to rant, but other than now being able to print on heatshrink, I'm not impressed. I think this labeler is hyped way more than it should be, only because it has the market for the moment.