I've used that Tennesean for about 25 years so I was pretty used to the flat bar(I don't think I was aware there was another)
Then I had a two tone single Anniversary from the 50s with a Dearmond, I found another Dearmond and then i saw a wiggly Chet style bigsby and I had to have one cause it looked so cool!! (In fact when I bought my Tennessean in Seattle a million years ago it was $700, had five strings on it and one pickup was on upside down, but I looked at it(I had driven from Vancouver to buy it) and went oooo ahhhh coool, played a a couple of gimpy 5 string chords and bought it!)
When I got that blk double anniversary(I think someone refinished a sunburst) I bought the bendy arm for the stock bigsby
I would say I'm more used to the flat arm and fine it quite handy, it's certainly less prone to coming loose, rotating etc
The round arms, look amazing!, are quite handy as well, round to get your pinky around nicely, but a little thicker.
The main thing I don't like about the modern ones is the stupid set screws into the aluminum frame. The one on my Anniversary needs to be attended to every once in a while, I should put some lock-tite on it. I think it only has one screw right now and that's not original as the tiny gimpy original one stripped quite easily