Yes I AM happy!!!
I'm not very familiar with the MkV, but I have no doubt the Axe would work very well with it. I think and important thing with effects placement is having them at the right point in the signal chain, before or after the pre-amp. I had originally tried the 4 cable method with an old Boss GT-3 multi FX unit but it was fiddly and complex, with difficulty level matching. And the Boss is old and not super-high quality.
Assuming your MkV has an effects loop, you can use AxeFX distortion pedal, EQ, Wah etc before the MkV pre-amp, other effects, such as the reverb, delay etc after wards, before outputing to the power amp section. And it is totally flexible, so each Axe Fx present can have the pre-amp amywhere you like in the signal chain. You can run parallel signal chains in the AxeFX, and you might even be able to do this with your MkV to blend two signal chains. I have not looked on that but some one on the Fractal User Forum would know better than me. I've had it 10 days.
The effects are quite simply superb. Very flexible too. There is too much for me to go through here. I can't compare with TC electronics, but I can't imagine how they could be better. I've read of others rating them "as good as it gets", but people with more experience with competitive units would be better placed to compare.
One thing to bear in mind is that AxeFX is a rack unit, so needs a separate MIDI controller for live use. I am lucky in that my Boss GT-3 has MIDI ouptut. I though it would take ages to set up and might not be ideal as a MIDI controller, but I just plugged it in last night and it worked straight away! I haven't worked out how to set up the expression pedal yet, but the patch changing works straight off. You pick up GT-3 or similar on eBay for peanuts - so I would cautiously recommend that this is not a bad way to get a cheap MIDI controller.
Another thing with The AxeFX is no headphone output. You need to hook it into another device like a recording interface for that. For me it is not a problem.
For this punter, I'd say the AxeFX is the best gear purchase I've ever made.