I have tried them all, some have improved features but some come with anomalies and problems. The worst was a gimal buzz that plagued some Pluses but not others. That buzz problem seems to be fixable with a gimbal specific update available here on the forum that works great.
About the only added feature that comes with Build 822/829 was a digital zoom [1x, 2x, 4x, 8x], which I think -and most here will agree is useless on a platform like this, especially since you have to stop recording to change the magnification. And for that useless feature we get a password locked calibration menu. To me this feature is not worth the update.
My Pius worked fine until I did my first update, then it seems like I have had one problem after another. All of them seem to be fixed now, but what a forkin hassle it has been! And for what? A digital zoom I never use? Oh please spare me that experience!
If I had your Plus with 757 and had no issues, I would leave it installed and go with it it indefinitely. If it ain't broke, don't fix it! This really seems to apply to Yuneec firmware.
@Ty Pilot is still using an early firmware and is having no issues whatsoever, and he has no intention of updating anything.