experiences of long multi cam on FCPX ?

A producer of music show for tv must change its hardware and software. He ask me what NLE i recommend, FCPX for me is the best especially for this. I've edited an half hour concert with 7 camera angles without any problem, but another editor say me that he have a lot of crash problems with more than 1hour program of 7 HD cam.
Does someone have some good or bad experiences on those sorts of long multi cam edits ?
Can I advice FCPX for this work ?

Several factors come in to play, it's not a one size fits all issue.

1- Mac model specs.
2- Media hard drive specs.
3- Camera codec vs optimized/proxy.
4- Third party software & plugins.

Any of those can interfere with app/system performance, not just FCPX, for any NLE.

Of course.
The producer, is going to buy a new mac pro 8 core and he have 8HDD in raid5.
The editor who had problems has a MacBook Pro retina 16Go ram and 1To Raid0 SSD Lacie, so it's not an hardware issue, exeept if one of those elements has an issue.
I've asked him it's library to test on my hardware . I also want to know, how he organized it's library, that could be also a part of it's problem.
Usually this producer work with P2 cameras in AVC intra 100.
I will try to solve its problems as soon as i'll have the elements.
But I want to know if someone have some experience with 8 cam angle of multi cam of more than 1 hour ?
Itv4 had problems on the "tour de france" with long media and the render of the waveform, with 8 long media it should be a problem on such library.
Some experiences ?

I did a live show that was two hours long shot with 7 cameras. Did it on an old iMac using proxy media and it wasn't an issue. It worked ok with original media but not as smooth as you'd like. I imagine a new Mac Pro would blitz it.

I do multicam all the time, with shows over an hour and have no problem. Definitely proxy for that many streams of HD on most systems.