Hi, I was on a 2 kites 1 board quiver: 10 + 16 m² and a small TT 138x35
This year, as I'm a new dad, I planned not to go out that much so I changed to a 1 kite quiver. I chose a Peter Lynn Synergy 12m² (yes, it's a foil!). I pulled out from the shelves an old directionnal board (207cm) which has a lot of volume for good float, very flat and straight outline. This board has lots of speed, excellent upwind and good edging ability which helps a lot in light wind. I can get out in 10 knots with it (I'm 63kg). When the wind hits 15 knots, I switch to my F-one SK8. From 25 knots, I change my 27m lines to 20m ones and can push my kite in higher 30s knots easily.
Getting the lines down to 20m does not make the kite behaving any different or worse to me. I actually love to fly it on short lines as it is more challenging to keep it in power all the time and it is so much easier for jumping as it reacts faster. I don't want to get back on 2 kites for the moment as I do not kite much but even so I think I would stick with one kite/2 boards. Perfect to me: I have less equipment to transport and don 't have to wonder which size to chose
Then when on the beach you have to tune it according to the conditions but if you know your gear, it's no hassle!