I found if you set the SP-555 as MIDI controller and audio interface with sync, you can sequence your patterns in FL's piano roll (MIDI track set up to the SP-555). Move the pattern over to leave the first bar blank. Go into pattern mode on the SP-555, set the length of your pattern (how many bars minus the blank bar in FL) and tempo, and when you hit the "sampling" button to start the count down of your pattern sequencer, FL locks in time and plays the empty bar with the SP's 4 beat count down. When it loops back to the empty bar, hit cancel on the SP555, and tada.. You have a perfectly sequenced pattern in the SP555 (providing you have no dead space on one of the beginning of your samples).

No need for quantize. If you have fixed velocity off, this maybe gives you better control on the velocities instead of banging out beats and such with your fingers.

I only use FLstudio for this and have my other synths and such off when doing so. My guess would be that you could do this with other sequencers/DAWS, but I haven't tried. It works for me, and I hate the pattern sequencer of the SP555, so I thought I'd share.

Sounds like you're complicating things.

What benefit could from from this?

Benefits:

You can use the SP as a MIDI controller - You can tap out your patterns by hand recording into a MIDI track (or just draw the patterns into the DAW's piano roll). You can use quantize while recording, quantize after, move notes around to fix mistakes, adjust all the velocities, and once you are happy, you can record the pattern into the SP's pattern sequencer.

Other stuff:

You can create loops/sound effects from VST instruments/samplers and sample them and/or record those patterns from the computer into the SP. You can bounce back and forth between the DAW and the SP to pan/mix/use DAW effects and etc. Remember, it did come with Sonar LE..

But if you like things minimum away from the computer, there's nothing wrong with that.