I never had a problem with their CS. Matter of fact I had a machine die twice on me & needed to reload their software & couldn't find my license info, they sent it to me within 10 hours of request, a little longer the second time, but did with no hassles. The program itself has never giving me 1 shred of problems or glitches & it runs over 10K songs 24/7 in a repeat history mode. Now being their karaoke section is still pretty new, that may change the stability - I don't know at this point, but it does look like a promising piece of software.
As far as proprietary format, I don't have a problem with that either - never have otherwise I wouldn't use MTU, although if this does what I need, Hoster MAY be replaced.......