PeGe, I have a MS as well as a 748. i actually got the 748, primarily for track use, after I got the MS. I would rate myself as a resonably good rider, 40 years experience, lots of track time in Porsches, but new to track use on a bike (just for reference).
The MS seems easier to ride quickly, as compared to the 748, but the 748 would be faster on a track (for me anyway). Not a lot faster though. It will lean further, I have not yet scraped anything (unlike the MS) and it has a little more power. It is also a little more stable, seems like the steering rake is more shallow (not sure how else to say it). Like more castor on a car. Riding postion lends itself better to going fast through corners (impossible to ride any other way, actually

)
I think if i was follow myself with the MS in the rear, i could keep up with the 748, but only because i was in the back.
I ride a 60 mile stretch of wonderful mountain roads (Angles Crest/Angles Forest Hwy) quite often, and usually I take the MS.
Hope that helps.