You send it back to FS for the warranty.
If it is flat on it's back, you simply pull the middle line and it will launch, if it is flat on it's front you pull both brake lines and it will reverse launch, letting go of one line sends it to the side, if you have a look at the vid's on the FS website it really is exactly as simple and as easy as that. The valves slow down the water intake so it is not common to find them sinking, have you heard of many cases?
If the LE is down on the water you can either reverse launch as above or just pull one brake line and it will turn while still on the water... if the TE is down on the water(after you pull the safety) put the safety pin back back, hook in, depower, and off you go. It has a drain system so even if it takes some water on, it will drain quickely.
You say foils cost more but how many LEI's do you buy, 3? or 4? perhaps, 2 foils are good for wide range, with the speed you can problably get away with 1 kite in coastal area's where the wind is generally better. Still as a long term foils are okay, the initial cost is there, once you bought the first set you are okay, you get reasonable resell value out of them, although I think as they become more popular the resell will drop a little. So the next upgrade is on par with cheaper LEI's.
Thanks for a good honest answer.