If you don’t already have a chainring you’d be daft not to buy a thick/thin IMO.
Clutch by itself with an E13 single ring with no guide was hopeless for me. Clutch and chainguide was reasonably good, but not perfect.
Clutch + thick/thin and no chain device has been the best of all worlds though. I did use a chain guide, but I’m not convinced it was doing a thing, so I took it off- if I can bounce my hardtail down fort william (including a little bit of turning it upside down and throwing it at the trees) and have the chain not come off without it, then I reckon it’s good.
(also I reckon that if you ever do get the chain to come off with a thick/thin and a device, you’re going to have loads of fun getting it back on- I’d sooner have a slightly higher risk of a drop, and a 2 second fix.)