Since STO is sunsetting Mac support starting tomorrow (2016-02-05), I tried using CrossOver to download it using the regular PC Arc launcher. Fortunately "Arc" is a supported app, and the default install went very well.The only notable problem during installation was the initial long hang at the "season" loading screen (currently "New Dawn"), which happens on first launch only, but takes 10-15 minutes to get past.
STO has some occasional startup issues after crashing, but these also happened with the "native" (Transgaming Cider) Mac client. Shutting CrossOver down and restarting everything seems to fix most of those, but sometimes the STO client leaves some kind of debris behind on crashes that take 2-3 restarts to clear up -- this happened with the official Mac client as well
I've used STO for several hours today with no unusual problems -- i.e., it crashes occasionally like it does for regular PC users, but generally is stable enough to use without too much frustration. It certainly seems about as stable under CrossOver as the now-discontinued Mac client.
There is some very transient graphics glitching which looks like a GPU driver issue during screen updates -- sometimes it flashes random text garbage very briefly. But this is brief and infrequent enough that it is no more than a minor annoyance. However, this problem is not present in the official Mac version of the game, so I assume it's due to something in the current Wine graphics drivers or the default configuration.