My opinion: The triple is definitely a more practical street bike and below 100mph is where its at its best. Its more of a "real world" bike, not a track monster, but is also more than enough bike for the average track day junky.
My previous ride was an 03 R1, which was a great bike, but it really needed to be revved in order to reach the meaty part of the power curve. Just like your 750, high revs = speed limit broken (on my old R1). The S3 provides plenty of hooligan enjoyment but allows you to do it at more sensible speeds.
The R1 was also a little, um.....small. I'm 6'4" and 110kg and I find the S3 to be a good fit physically. I commute on it every day and hit the twisties on weekends and so far have nothing but praise for it.
Hope that helps