Was it direct to FOH, or into the return of an amp/Poweramp+cab?
If it was direct to FOH, did you ensure that the cab modeling was turned on? Of it was into return of an amp, did you ensure cab modeling was off?
In the past I have managed to get great tones out of the RP series in FOH settings. Dressing the lead tones in a good heap of delay and reverb does a great trick, because digitech's RP reverbs were awesome. Their chorus was great as well. Their tube screamer and DS-1 models were very comparable to the real deals as well (I've tested before).
Yeah like JF said, if you had a cab/IR loader, it would have been awesome. Because like any unit, the cab modeling is the weakest on these.