I had a 2 handed backhand for many years and only switched to a 1 hander last year. My, what an improvement! Number 1 is mentally. Before, with my 2 hander, whenever I had to hit a backhand, it was like: "Dammit, another BH, can't run around this one." Now, with the 1 hander, it is: "Yes, I get to hit a backhand now!"
A 1 hander is just more fun to play with
On return, it can be a bit of an issue, until you get the timing with it. After that, I think its actually EASIER to return with 1 hand than 2. Plus the slice comes more naturally with a 1 hander.
As for the high balls, you just gotta be quick, and take it on the rise. In cases where that is impossible, the jumping one handed backhand must come into play. Actually, I try to get enough force from my legs into the shot that I naturally leave the ground at least a few inches, both FH and BH. So nearly every shot, I am exploding off the ground.
Overall, 1 handed backhand is the shit.