Inflatables lose a lot of speed in turns due to their shaping constraints (imprecise rocker, thick rails).
So they do not work well for top turns, but modern, good quality ones can work surprisingly well as long as you do not expect to generate speed nor attempt vertical surfing. They are OK for kind of "relaxed longboard" surfing. I have a friend that has a 10' one, and he has quite of fun with in small waves. The added volume make him take off on anything.
Look for:
- no more than 4" thickness
- pulled in nose, (wide nose tend to stick to the water on inflatables), and maybe tail if not on micro waves
- hard edges on the rear (otherwise they have a lot of drag) with rubber rail edges
- max stiffness: basically, the more pressure the board is rated for, the more the manufacturer trusts the quality of its buiid. And the more you can inflate them, the better
- short length: longer lengths will amplify inflatable issues in surfing (especially fuzzy rocker), shorter lengths somewhat mitigate them.
In this video you can see a modern board in action. Look how it doesn't flex under the 100kg of the rider, and how he can dig the whole rail in the wave without too much drag
Compare with the same brand 6 years ago: you can see the progress in stiffness (that happened with most brands)
And this vid show what to expect with an inflatable: 8'5" enhace handling, but digging a rail/nose is still not the same as on a hard board. Note that this model didn't have yet the hard rear rails, so is noticeably slower than a modern board with them.