Riffs, to be honest, are VERY like looped Intros, the kind where you play the initial chord, and then it plays changes.

For me, it would be the perfect way to play a solo that uses a lot of bender, or (if you switch off the chord recognition) a really outside piano solo (that didn't send the chord recognition bananas) or pick up another instrument and solo, or go out front and mug with the audience, or anything you'd like (including that well deserved drink ), but there's no reason it couldn't have a nice solo in it for you to sit back and listen to...

Thing is, Ketron's Riff is ONE preset set of changes per style, and so far, no idea if you can add your own (I don't think the SD-1 could). Me, I'd rather have control over the changes....

On your Korg, you could import an SMF to one of the Intros, and loop it (can you loop intros like you can fills, with a double-tap?) to get pretty much the same thing, only at least YOU can program them (make an SMF of the arranger playing what changes you want, save it and import to an Intro). Sure, you lose an Intro... but who uses all four, anyway?

If you can't loop Intros, just either keep hitting it in the bar before it finishes, or put Intro on a pedal and hit that...

Four Intros and Endings on most arrangers, and who uses maybe more than one of each? That's six patterns you can put in... Intros for jam loops and break/fills or longer fills, and Endings for pauses (use autostart to come back in). There's a lot you can use these unused sections for. If you like Ketron's Riff feature, you can do it on your arranger even if it isn't in the basic feature set...