Boo,

I have gigged at least 20x so far with the Carvin AG100D and it does an excelent job for what I bought it for (small room gigs)light weight and Great sound for arranger keyboard and vocals and mini discs playback.

Again for the bigger venues The Mackie SRM450 speakers are unsurpassed in my opinion for power, clarity, convienience.
As far as stereo, depending on the size room and amount of people I will use one or two speakers. Stereo is not a big thing for me and to be truthfull most people in the audience wouldn't know the difference anyway.
The Solton X1 does an excellent job in mono or stereo. I would suggest (only if you need the power) to get ONE Mackie SRM 450 and down the road if needed get another one.

Donny