fgx slays. fgx>ozone IMO.
i don't even know wtf itp does.
it's really good to leave on sometimes during a mix so you can get an idea of what your mixes will sound like mastered. a few mixes i left it on like half the time (that's a lot) and then take it off and i find that in today's world using this approach helps preserve your drums in rock mixes and balance the bass and vocals well. the most common mastering stage changes are gtrs up, drums down, and bass up. fg-x give you a good perspective so you can set them accordingly. at least for me...
It can be a bit resource heavy for this if your DAW is at all stressed during mixing. You can still get a lot of the effects of maximising with a less specced limiter - it may not sound as good for rendering but if you're just after hearing the effects of the 2bus on your mix you should be OK.
A.