I think the other big attraction is you can make it what you like.. if you want lighter and shorter, machining a barrel to fit is simples, and getting back the lost energy is easy. If you want shrouded, bolt on the MFR unit. If you want gazillions of shots, fit a bigger bottle (400/500/600) and a reg. If on the other hand so only want 150 shots, stick with 280cc or even 200 cc. If you want a .25 cal, it's only a 30 min job. single shot for HFT, mag for field (OK, many guns can manage that, but a good number are a PITA to single load).

So many options