That looks a very nice bike, pity you've sold it. As they were so light in comparison to even 753 tubing, they were very popular in the 80's for Time Trialling before 'aero tubed' low profiles became 'de-rigeur'.
Mind you, I think they also made a LP version, isn't there one on here somewhere - from Holland?
I have a 1983 Vitus catalogue which shows 3 tube profiles for the Down and Seat tubes. The normal Round, a 'Lozenge' shape with 6 'flats' along its length and an aero'ish 'Teardrop' profile. However, the top tube remains Round and the special shaping is not along the full length of the other tubes as the lugs are still the normal ones.
I can't remember seeing anything other than the Round tubed ones myself.