Well- moving from the RC-20 to the RC-300 is like night and day. I can do so much more and have been pulling this new toy apart. I never got to play with the RC-50. Despite the stereo 3 independent tracks for looping, it has 3 hours of total loop memory space, and 99 patches to store loops. I loop live so the memory location is irrelevant until I found out you can record direct audio(like a mp3 player) into it and loop said audio. This might come in handy for potential backing tracks if need be. You can even turn off the loop track and make it a "1-shot" and play the recording through once- like a backing track. Not bad when you have 3 hours and 99 locations to store your backing tracks- fire the band! If you record in one track, and overdub onto your recording, hold the play pedal down for that track for more than 2 seconds and it deletes the overdub without deleting the original recorded track. That's a plus considering I was afraid of over dubbing in a live setting with the RC-20 for fear of making a mistake an having to start EVERYTHING over. As far as stopping a loop- and this is cool. You can Immediate stop the loop, stop at the end of the loop, or, ready for this? Fade the loop out... Damn that's cool! If you have 3 tracks going at once you can mix the output volume for each track independently. You can also pan each track as well (stereo) and assign each track to a specific output - main, sub, and main+sub. You can loop sync all tracks- or turn loop sync off for any track- another words sync 2 tracks and not the third- not sure why I would ever want to do that- but who knows? You can attach external button foot controller to this and assign what specifically those extra button foot pedals do- this is pretty cool because there are built in effects that can be triggered, or you can us the add on pedal switch to switch through patches, or set tempo- or start track recording to name a few. There is also a built in rhythm capability with different drum beats that you can play with. You can even change the timing of the drum beats from the standard 4/4 timing to all kinds of funky timing like 14/8, 7/8, 6/4, 3/4 etc. additionally you can set up the drum beats to count you in and then stops playing when the first recording ends. Pretty cool to Get your timing down, an mot have to hear the same pattern over and over through the looped performance. There are quite a few different drum patterns. Too many to count! There are loop effects that can be used. Such as a vocal processing and guitar modulations such a tremolo, distortion, chorus, delay, flanger, etc. and you can assign each effect to any one or all of your loops. I tried the GT-BASS effect transferring my guitar to a bass sound and it was god awful and painful to hear. The distortions and other effects seemed OK- but not that botique sound from custom pedals. There is a MIDI connection- I know nothing a out MIDI. There is also a USB connection to download wave files and loop them as well from your computer. You can set this up to store files back and fourth- or to play audio from your computer through the RC-300. So much for only having 3 hours of memory? Damn-with a laptop it's unlimited! Hope that helps in the event anyone may be interested in upgrading. I'd love to post some audio- I just don't have the recording capability to do that.