I have an ACE boiler (NOT the brewer, just the boiler set) myself. I have arthritis in my left hand, wrist and a bit in my shoulder, as well as near permanent sciatica and shot knees. I lift the bag out by putting my SS mash paddle through the handle loops, then getting my wife to lift one end whilst I lift the other, then I whack a cake cooling rack on top of the boiler to rest the bag on whilst it drains. Once it's mostly drained it's much lighter and I can manage it fine on my own. It's a really good boiler kit for sure though, one tip for you if you get one though, use a couple of pegs on the handles to raise the bag higher (it hangs just above the liquid surface otherwise, and you end up with grains getting loose), it has plenty of length in it to do this but the handles just don't sit quite right without the pegs.
As to efficiency, with a fair bit of advice, research and tweaking my process, I'm now getting from 82% to 86% measured kettle efficiency. The variation now is dependent on how much RO I mix with my tap water (more RO = higher efficiency due to lower mash pH for me, but too much and I risk not enough calcium etc). The biggest improvement though was learning how often to stir, and daft as it sounds HOW to stir the grist whilst mashing. I started out doing it too carefully and gently, you need to really get it all off the bottom of the bag and into the water column. I find I can get away with stirring every 20-30 minutes throughout the mash (it's a balancing act between maintaining mash temp and stirring enough).
The only problem I still have is, I get a lot of very sticky trub. I even tried a longer bazooka in there but it still clogs by about 5 litres transferred. So could be the bag could do with been a bit finer possibly, as seems to release a fair bit of flour.