Thanks for a great plugin. I have used it to copy sites from their development url to their final url using the migration mode. And it works just fine - under php 5.2 :)
When I switch my host to 5.4, I can't activate WP Move as it throws a "critical error" without any further details.
I have overcome this problem by switching back to PHP 5.2, but I'll like to switch to 5.4 since I've head rumours of performance gains :)