I was on the fence between a Lock Right and Spartan when I got mine. Went with the Lock Right because I knew it was tried and true. From what I understand now though is that the Spartan is a decent locker. It has a larger center pin than the Lock Right and Aussie so it can take a little more abuse. I wouldn't be afraid to put it in if I had it to do over again.
If you're putting it in your front axle and you still have the CAD it will be like it's not even there in 2wd. Best of both worlds.