Getting a kernel panic, suspect filesystem corruption

A bit of history... When I first got the machine it had Yosemite on it. The upgrade failed, then every time I booted launchd would panic when trying to login. A internet restore then failed, as it wouldn't even format the disk, then failed a 2nd time. I managed to eventually use diskutil to wipe it completely, then install again from the internet. When upgrading to 10.11.3, I also had problems and had to repair the filesystem again. I'm wondering if it's only exhibiting problems when under load & doing plenty of IO.

Anyway, I just tried to update Xcode to 7.2.1 via the Mac App Store, and the machine is kernel panicking again.

I've just about had enough - This is my 3rd MacBook Pro (I've also had a Mac Pro and a 27" iMac in the past) - I've never had so many problems with Apple hardware, normal it just all works, so I'm convinced this unit is defective. There isn't a Genius Bar appointment near me for another week, either.

Details:

Model Name: MacBook Pro

Model Identifier: MacBookPro12,1

Processor Name: Intel Core i5

Processor Speed: 2.9 GHz

Number of Processors: 1

Total Number of Cores: 2

L2 Cache (per Core): 256 KB

L3 Cache: 3 MB

Memory: 8 GB

Boot ROM Version: MBP121.0167.B15

SMC Version (system): 2.28f7

Panic link: http://pastebin.com/cA3mnkKM

Thanks,

Phil