I've been using MM products since 2005, way before Numark took hold and (IMHO) shelved it in order to promote what they believe will make them more money - Apple Apps such as the abysmal idj product.
I use Fusion 7.4.4 and have had no problems using it live in club/village hall/internet radio settings. I generally use it as a basic mix tool ( i.e. track A into track B ) when playing live, with the odd bit of cut n paste lunacy for good measure.
Where it comes into it's own for me (and wins out over Ableton Live - again IMHO) is in the ability to create 'studio style' power mixes of the sort I used to have to painstakingly piece together using multitrack recorders
back in the dayI still love using Fusion, even though I'm on the learning curve with 2/3 other products (some of which utilise timecode CD/Vinyl so I can keep the
old skool skills up to
scratch so to speak!smile and whenever the Mix bug takes me it's always Fusion I turn to first!
I have history with both Tepmix & MmeFly and know that they both know what they are talkign about - nice to see some familiar faces here.

R.