Grahamette, this ex sailboarder managed to get up on the board after a few lessons / sessions totalling about 3hrs.
Without lessons it would have taken a lot longer and my confidence would have been destroyed through crashes.
Getting up is the easy bit and upwind will be a no brainer for a sail boarder but from that point it gets a little more difficult working out transitions, stance and good kite control
After your first few runs you will wonder why it took you so long to trade the sailboard for a kite, there's no rig to look around or through, if you fly the kite high and wear sunnies you won't see the lines or the kite and it feels like you're blasting along with no motive force !
Go for it