@Wibble I mean, I haven't weighed the system, so I'm not sure, but to play devil's advocate for a second, I'd guess that, since the batteries, pump, etc are dense, you need less ballast weight. From there, since you're effectively adding weight/reducing density after you get in the water so you can skimp out on a bit more lead. Lastly...yeah, most of the comparisons are to "poodle jackets" so as I've said above, I feel like a minimalist setup could likely match or beat Avelo on weight.
As for the reserve buoyancy...they claim to have done rescue scenarios that say it's fine? I don't know a lot about that, as I'm not a rescue/safety diver. I do know the system comes with a "horsecollar" dsmb, but IMO, yeah, what you're pointing out is part of what reduces the versatility of the system to being limited to one type of diving.