I've been using whoopie slings on my HH Exped. for awhile now and love them, but ... I got tired of toggles. I have cinch buckles from AHE on my wife's ENO and they are just so much easier to use than even whoopies.
The other issue I had was that I am using my climbing carabiners to clip on the tree huggers. What I don't like about that is when I'm using smaller diameter trees, it pulls sideways on the biner pretty substantially and, being a climber also, I wince every time I look at it. Of course, I could buy dutch clips and solve that issue, but that takes cash monies that I have to spend on other hobbies ATM. C'est la vie.
So, I started thinking about how I can make the whoopies behave a little better and the end product is actually pretty simple. Instead of using a toggle, I clip the whoopie sling and one loop of the tree hugger to the biner and that says connected permanently (no leaving stuff behind!) Then I wrap the hugger around the tree (once if it's a big tree, twice if it's small) and marlin spike hitch the free end of the hugger back to the carabiner.
This keeps all the pieces connected, gets rid of a piece of hardware that could be lost, keeps my biner from being side-loaded so to speak, and makes it dang near as fast as a cinch buckle set up.
On larger trees, I don't wrap twice, so the tree hugger is not actually cinching the tree, but there's plenty of surface area in contact with a larger tree to keep you off the ground. If you were hanging from a smooth barked tree in the rain, this could be an issue, but I'm unaware of any smooth barked trees that are also too large to double-wrap... at least not around here :-).
And, at the end of the day, if you find a place to hang where you can't make this work, you pick up a trail stick and move back to the standard toggle setup.
So, some day I may end up getting some dutch clips for my wife and some lighter weight carabiners for me. I've only hung off this setup in my yard though, so it could still turn out a disaster in the field under wet conditions. Hopefully I'll test it out on Patriot Day!