"RiotAir" have a hand luggage limit of 10 kg per person, which if you use one of those small, lightweight wheely cases is not too bad. Unless I was camping or something, I'd have no problem complying with that for most trips. If you found you were a bit over the limit, you could stuff heavier items (books, camera, etc.) into your jacket pocket instead of your case, which is a tactic I often use. You can always stick these items into your case once you've cleared security.
I've flown with them quite a few times now, and despite the spartan nature of the overall experience, the punctuality has been surprisingly good.
Good luck though, because it's a tighter connection than I would be inclined to risk, unless they were to start issuing through tickets.