Since you tried a few different methods, was BIAB primarly for convenience? Do you find that your wort is cloudier with that approach? I tried a small BIAB on the stove and my gallon primaries have a lot more trub than I see with this approach.
It is for convince, and there is a fair amount of protein that goes into the fermenter, but I cold crash and my beers plane beers come out crystal clear.
"Efficiency" is highly overrated. If you are at 70% plus already, you are fine. You can spend time tweaking your process to get that up a little, but getting up to 80% is only going to save a couple bucks a batch. Obviously, it's nice to save those couple bucks, but it is a pretty small benefit. It's much more important to be consistent so you can can brew the beer you want every time. eg if you are consistently at 72%, just plug that into your software and you'll be golden.