I bought one new, and two others used, and always kept one working. The shot system is really a double edged sword. Out of the water, there's no way to carry the shot separately. So it particularly heavy too, when you have a tank attached (or twins) which brings it to 120lbs!. In the water, its sweet! Super clean. In fact, there really isn't anything as clean. Nothing hanging. I actually plan to throw away the bladder and hose, since the inflator hose is cracking on my last ATPAC. However, I'm planning to look at threading on a brand new wing from another manufacturer. I've got two or three of the nylon back systems and collected about 60 lbs of shot from all the used systems. The integrated weight system is super hard nylon back case. None of any of my back cases have worn out.
The key to proper shot maintenance is to simpy shake before each dive to make sure the shot is fluid and make sure you dump it out once a year or so and lubricate it. I have had to dump the lead shot during a real emergency ascent once. It poured right out.
Bottom line, its painfully heavy out of the water with twins especially. But if clean rigging is what you want, I can't think any cleaner weight system. I admit I prefer old school equipment thats tried and true. Perhaps that's why I still snow ski on my 207cm GS skis too!
but Nothing bust through the Cascade crud and hauls arse down a steep slope, like them. I'm an old fart that leaves the short ski drivers in a my plume. The point is, some of that old stuff, does have some unique appeal when it comes to performance. In about 10 years, I'll probably have to go lighter and shorter on my equipment choices, but I'm not their yet.