Personally, I have yet to find something in the Mango release that simply "doesn't work." Quite the opposite, in fact-- for a beta, I'm remarkably impressed at how fast and stable it is.
Now for the search, that IS a beta feature and I would point out that just like Android's voice capabilities it is HIGHLY dependent on your data connection, so if you're in a low-coverage area, yeah... might be buggy. But if that one feature in a BETA is a deal-breaker for you, I would say YES, you should revert back to NoDo, and in fact you shouldn't be messing with betas at all. Ever. I don't want to be a jerk, but if you're that sensitive about the matter why would you ignore all the "use at your own risk" disclaimers in the first place?
Heck, I use my phone for work in an IT setting, so I'm right there with you, BUT, being a sys admin I am techy enough to deal with the bugs (to which I say again have been unnoticable in my experience), so I took the chance on it (keeping my NoDo restore point and my EVO handy at all times).
As for the ringtones, I forget if it was an earlier post in this thread or in the Arrive forum thread, but I agreed it was incredibly irritating means of assigning ringtones, but I fully anticipate custom apps being developed to simplify the process. The Windows Phone team blogged about the matter and promised that it would get easier, for what it's worth.