I am trying to get a general discussion going about these two amps for a wide range of music.What are you using it for? What are you playing. I've only tried the Cube 30 and Spider III 75w. Between those 2 I'd go with the cube. The Cube was much more natural sounding and not as "sterile" as the 75 in my opinion.
The spider IV and spider II are VASTLY different amps. The spider IV is really decent for amp tones and FX - directly from the m13 pedal board BTW.I have only used a spider 2 and know I use a roland cube 20 x. I find the cube a lot warmer sounding and the power amp sqeese feature is brilliant. On the other hand though, I have had vetta 2 hd 157 boss gt 8 and a shitloads of tube amps so I know what I like from an amp. For portability and very good bass response the cube 20x is my weapon of choice. It,s simple to use and the tones are very nice for a digital unit.