I think the wifi express logs multiple entries for temperature/rpm data, and it also allows you to save/load multiple profiles with single (or multiple) ESC/s.

I'd wait to hear others' responses though - while I've used both and have the app, I haven't bought my own express yet (just borrowed friend's).
The app is very nice, Hobbywing has nicer/neater software than Tekin, also seems bug-free. Works well on iPhone too.

If you already have the program box I don't think there's any huge functional benefit, it's just very neat and convenient.
The app has a demo mode (for each HW ESC) so if you like, you can install it on your phone and have a play around before buying anything.