I work as a duty manager at a pub and have a bit of experience with these kegs.
When I first saw them, I thought exactly the same thing, "I wonder if I could use them."
Firstly, to properly dispose or recycle them they need to be depressurised. This is done by releasing the pressure through the coupler without the gas fitting attached so the pressure can vent, then u need to pierce the inner bladder with a sharp tool inserted through the hole in the base. So if you wanted to refill them you will need to make sure this isn't done.
The other thing about these kegs is that they are completely sealed. The plastic fitting wont come off or "unscrew" so anything going in or coming out will need to go through the coupler, I imagine, because of this they would be a bugger to clean. This is about where I lost interest in using them. Couldn't guarantee that I could clean them properly. Also there is the problem of the coupling fitting wearing out. Like the others, I reckon you'd get a dozen or so uses out of them before u had issues.
I have found another use for it though..... I am currently in the process of building a portable keg setup that will fit a corny using the plastic outers of these kegs. I'll post pics once completed if u wish. It's been quite the project but its finally coming along....
