Rolf,
When we bought the Taipan 5.7, we had a hard time deciding between the 4.9 (which turns into a F16) or the 5.7. We are very happy with the characteristics of the 5.7.
You are of course right that with JIMI studying in Trondheim, less sailing will be done with my preferred sailing partner, and that may churn up dreams of a boat that may be sailed single-handedly. Namely a F16.

With the 5.7, being underpowered is not a problem, after all the boat was designed for crews >150 kg, and we are 145. So I think a 1 m taller mast requires widening the platform.
Stein