Had about 10 sessions on my 85L now. Does what the box says, gets going really easily especially if you can point it down a little bit of swell. Works best on flat days, not ideal for choppy messy conditions, this type of long and narrow board aren't as stable as your normal wider wing boards and take a bit of getting use to but once up it's super agile, the narrow width means you can tack harder and ride closer to the swell where you seem to get more wave energy. I'd go bigger than you think, not much penalty going the size up. I'm 70kg and have tried the 100L too and if I was ordering one again I'd have gone the 100L. Coming from straps it does take a few sessions to get use to no straps but you'll find you move your feet around a lot more than you think. No problem once you get use to it.
My biggest wing is a 3.5m and ride a H850 foil with mine, it gets me going in about 1.5 knots less than my short board. Interesting thing is I tried it with a 5m which I normally hate using but on the Swift it was great. You ride 3-4 inches higher above the water so tip clearance isn't a problem when pumping. It means you get even more benefit out of a bigger wing just because you can get a better pump.
I've started using a 75cm mast with it too, bit less drag when getting going and water is usually flat so length isn't an issue.
Here are a couple of clips
www.instagram.com/reel/C3kaBlwvmQq/?igsh=aXVvdmV5dG9mZ2lmwww.instagram.com/reel/C32H5K4votl/?igsh=MWlqa2w5ZTk1YTJndA==