hey man - I got an RC505 awhile back, its the best looper i've ever used by FAR. I really recommend it to folks, its a crime it didn't get more attention from the electronic community as it's one of the first to not be built 90% for guitar in mind.....great for samplers/beat box/rap/keyboards.
That being said, yeah you can use it as a multitrack in that fashion, verses on different pads and you'd stop/start to switch between them...you can also make a pad a 'one shot', like turning off gate on an SP pad, and you'd hit it once to trigger and once done it stops....there is another thing (I have not tried this) where the pads are in a 'mute group' so to speak, so you hit pad 1, then pad 2, and pad 2 would stop pad 1 - this would be more like a , verse/chorus/verse method where each pad had the vocal AND the music
Good luck, let us know if you get one.
Oh also, the effects on it are veeeerrryyy nice, they are SP-esque but some of them are much higher quality.
I need to make a demo video of it in use, but my skills on it are moderate at best right now
