In depth analysis and attention to detail are much appreciated. I particularly like your on line selector where users can rate boards in order for given criteria.
At 68Kg I think I need a 53-54cm 68ltr board, my current wave board is a 2006 RRD Hardcore Wave 61ltr /51cm v fast off the wind down the line, loves long drawn out turns but not the easiest to get vertical on, but that could just be lack of technique.
I would like to go down the Quatro route but think Tempo and Quad are too big leaving Rhythm, which is a pretty specialised dtl machine, unfortunately most of my sailing is South coast x on with occasional trips to Gwithian.
So I have started to consider JP Twinser or Quad in 68ltr size.
From your introduction it is clear both boards have a place for given conditions, twin x on small waves extra loose and playful, quad x off / x shore dtl bigger faster waves if I understand you correctly.
JP claim their quad is convertible, to what extent would you support this claim?
As I understand it their Quad has shorter fin boxes so clearly there is a difference in where you can set the fins in twin mode, is this significant?
Do you notice any significant reduction in performance when using quad as twin due to extra fin boxes, do you tape up or blank off unused boxes?
I have both 68l & 74l in quad/twin, and chop and change as I desire.
Board works great in both mode, and pretty much as you describe.
In cross-on, or in smaller waves cross off (under shoulder high), go for twin, for looseness and snappy rail to rail and tail slide.
For bigger waves down the line sailing, and overpowered conditions, the quad will give you the control.
Quads kind turn like on rails with loads of drive, twins more snappy and slidey.