There is no need to use a sequencer when you are converting midifiles to styles with One Man Band. By default OMB will convert all the chords in the midifile to standard CMaj7 chords. So you can paste the complete midifile into one large Main A variation if you want, without any additional editing.

If you do want to edit the resulting style you can use the built-in tools. Edit single events, record extra notes, copy and paste tracks, import and export tracks to merge different styles etc. You can play the style on your keyboard (with the built in real-time arranger feature) while editing it so this works much better then using a seperate sequencer.

The only reason why you should want to use a separate sequencer is when you want to record audio tracks to the music that you created with the arranger section. In that case you can export a midifile to a sequencer because OMB does not record audio.

Jos