Hehe ! That's cool !
I would think with surface tension as you mentioned, you would want to ramp up the throttle quickly and make the break from the water as fast as possible. I could see where a slow spool up to lift off would "stretch" the water clinging to the floats. Firewall that baby and I bet it will shoot straight up off the water. Granted, maybe a little crooked(still some surface tension) but better to correct for that at 10 feet altitude than to take 'er swimming. You're a braver man than I !
Thanks for sharing the pics.