The Kumo has a pad sleeve which is good for a sit pad. Just something to note. Could fit a bigger pad (eg a 1/8 torso pad folded) but check with them. It isn't meant to stretch as much as the sleevse of say a mariposa or G4. But if you are a neoair user, for example, having a pad sleeve is perhaps not that helpful to you.
Similar sort of sizes (and frameless, webbing belt options):
Zpacks Zero, "Medium" (That's medium volume option, torso length is customizable). Many many options to get it just how you like it. Its kind of like a fishing rod blank in many ways, its a pack blank that you then build up from.
MLD Burn. 32L main compartment.
I've not seen either of them ('cept handling some Zero's and a 2013 Burn in a store in Japan briefly a couple of years ago), but I'd hazard a guess that the 2015 Burn might have a better fit profile as it now has curved side panels, vs the Zero's more simplistic construction (basically a cylinder of cuben with straps attached). But both packs will have their own specific niches which might tempt you either way. The customizability of the Zero is definitely pretty cool.