slash - depends on the amp - tube or SS - what size/kind of speaker. A 65W tube amp with a 12" Celestion (or 2) should do the trick. A 65W with a 10" may bottom out with heavy riffs - I have a 60W Peavey (tube) w/ a 10" speaker - ok at low volumes, but wouldn't work on it's own for a gig. (speaker gives out on heavy lower chords).
The RP200 - ok, but it's a "cheapy" processor. Depends on your style of music also - Digitech, IMHO, produces a very synthetic sounding distortion. If you play metal - I wouldn't get it. After trying all the BOSS and Digitech processors out there - I opted for a Korg Toneworks AX1000G. They make an AX1500G now - if you tried one I think you'd be impressed.