Before I mention midi live recording issues, I'll mention that sample and re-sampling that it does have to be stopped first to do which can be a big issue for some folks. That can be a deal breaker issue and why I thought I'd mention it right off the bat. You can however do some delay input sample looping without stopping, not really the same thing and is more a simple digital effect but can be fun to mess with on the RS.
It's problem with realtime midi recording while continuing to play is a bit strange because it stems from the fact the RS's phrases in pattern mode do not always have to be the same length. Phrases of dif length can be a huge huge bonus compared to and over other loop/pattern based, groove style oriented sequencers, not many can do that, so don't think that is anywhere near a bad thing to have on a bitchen, full out 16 track desktop-sized sequencer, not to mention it has it's own 'decent' internal sound... Also, It may be different and work fine in song mode bouncing tracks, I'm not sure, but I'd think the idea would be to loop your sequence after recording it so pattern mode will be the focus here.
With firmware update 1.2x you are able to bounce around tracks that have the same phrase length while staying in record play mode. If you want to bounce to track that has a phrase of different length you have to get out of record mode while still playing then select the track and go back in to record mode. It is doable while staying in a live play performance but it is also easy to accidentally hit stop or mess something up in that process. I usually try to keep all my phrases at 4 measures which is default and can help eliminate a lot of confusion down the line if you decide to use pattern chain and convert the chain in to song for things like recording song wide sweeps. The other thing is while in step record mode you always hear the note when played at the time that you enter it on the step which could or couldn't be a problem with external synths, I'm not too sure, but you can avoid this by going in to grid/x0x rec mode which doesn't play the notes when entered but that mode is better for drums and one hits rather than if you want to play/rec synth chords. Also in step record there is a rec overdub and a rec overwrite which might be pretty cool for different reasons if one way or the other is your plan. Another thing if you choose to use, is that note quantize upon recording notes live is not realtime but I do think that the notes will be aligned on the second pass, but don't quote me on that, however I do think that is what happens on it but not 100% sure as I haven't used note rec quantize very often on the RS.
So, you do at least have some options and is fairly flexible for attacking different types of live/realtime performances on the RS. I'm not sure which is or will be the best or if one is better over the other, usually I pre-sequence or program all my stuff (I love the RS's step sequencer mode which for me is quicker and more effecient than using any of the DAWs) and then I punch the tracks in and out with mutes usually and tweak voices wile performing live. I haven't done much live sequencing and playback on it actually, it is more like I'm doing live mixing than sequencing during performances with it. An awesome companion to have with the RS for live mixes is a Peavy PC-1600 so you can fade multiple tracks or all at the same time instead of punching mutes and or dropping phrases in out by changing sections. Another RS is also a great companion
Lately, I've been having the most fun with using an AN-200 and DX-200 at the same time with the RS7000 however they have their own sequencers so I just have to sync their clocks. I could go on and on... I'll stop now.