Wind: ~12-16mph
Board: 5'7" quad surfboard
Style: strapless waves to flat water
Weight: 135-140lbs (62kg)
Length of time with kite: 1 year
Bought the Speed 3 19m deluxe for light wind from all the foil lover reviews. Setup is easy, but not really faster than setting up a 10m switchblade (leaving lines connected, more on the 10m later). Packing up is about the same because it's a pain to squeeze all the air out. Self landing when the wind picks up is hairy at best. This is a real issue when I don't have 300lbs to hold it down. Add the time for packing up a twisted kite after deploying the release and the "quick" setup/packdown isn't really an advantage. The kite is well engineered though, never had an issue with the bridles or inflation.
Light wind, it pulls like a train, and goes upwind...when there's enough wind. There's definitely pull, but it doesn't really go that well upwind in the really light stuff. It seems the kite doesn't sit forward enough in the window. You can depower it, but not too much where the triple depower feature kicks in. In ~10-13 mph wind, the kite just doesn't work with my surfboard (could probably do it on my old spleene session). At ~15-18mph and being a lightweight, there's not enough depower. So at 140lbs, either the kite falls out of the sky, or I'm overpowered.
Turning speed, didn't expect it to turn fast, and it doesn't. Waves? forget it. In the wind speeds where it's comfortable, turning speed is non-existent, especially while drifting. In <13mph, the kite needs work to stay in the air. It definitely floats more than a LEI, but so what? It's useless to stay in the air if there's no power to get you going. Back stalling isn't an issue as long as you fly it as you should and the mixer is tuned.
So what was my solution for light wind? Sold the 19m and got an Aguera race board + 10m Switchblade. It gets going in the same, if not less wind than the 19m + surfboard. The race board keeps going upwind until the kite falls out of the sky. Now, you could use a 19m + race board, but why bother when the 10m works at our weight. When the 10m falls out of the sky, the 19m will too. Edit: one other drawback of the turning speed on a race board is that you can't loop it in transitions (in very light wind). The race board can build amazing apparent wind where your kite will fall out of the sky in transitions. I've had times where my 10m Switchblade will stay in the air with several loops (race boards don't "slip" like TTs, it's like standing on land), but the 19m would just hover in the air for about 2min trying to turn around because the wind is so light. Sure it stays in the air, but sitting on your board waiting for your kite to turn around ain't exactly a blast.
That's my experience with light wind foils. Hopefully it helps others in the same weight class decide on their light wind quiver. I'm sure the Speed 3 19m works great for someone heavier as seen from all the reviews, but it didn't work out for me.