Probably so. But there are dangers. You should expect that these apps might have portions of them that are buggy, some might have regressions from a previous version (i.e. features that worked before & are now broken), and in rare circumstances may hose your phone. Stuff happens.

I think the reason people emphasize the dangers is that you have newbie users installing some alpha version of an app and are scandalized when something goes wrong, bad-mouth the developer, and expect others to come to their rescue. Well, it was in extras-devel, and you took the risk of playing with it...

Yes.

I would not say THE solution. Sometimes all you need to do is uninstall the app. For many problems, reflashing would be swatting a mosquito with a sledgehammer.