I have a 2021 Cervelo S Series with Di2, and it has the aero bar with fully integrated cabling. It's a clean, nice look and *slightly* more aero. I mainly just like the look of not seeing any cables.

I have around 500 miles on it now, and there are a few practical considerations to consider. Do you actually ride on your tops? I don't, so I don't care about the flat shape, although I do find it comfortable the few times I've used it. But if you do like to ride on your tops, you may want to lay your hands on the bar to make sure you like it.

The other big thing is if you ever want to change your stem. At least with my bike, I'd have to disconnect the brake cables and rebleed the system afterwards with a stem change. But you have a lot of time on a very similar bike, so I think you should be able to get the right length stem now. Unless of course you like to constantly tinker with your fit.