I find that app connect is really lacking in features. I do understand there is a fair amount of complexity but come on, with the team apple has, the importance of beta testing and real world issue I find app connect very lacking.
Looks like once a tester is added you can't even edit their firstname/lastname - why! I can see changing apple id being a bit (but only a bit) of an issue, but their name?? People get married and change their last name, sometimes we do a typo and get a firstname wrong.
Also having a tester test on two devices is a real pain. If they add testflight and use redeem code and then later on add a new device one is unable to resend invite for them to use new redeem code on new device is an issue.