I'll repost feedback about the X12 on this forum. I keep forgetting to do this, but you can also find user feedback/testimonials about my pres on this page.
Here's one I recently received:
Just wanted to give you a quick note about the X-12.
It's in my nice 500 rack and almost every day up and running.
Did some heavy band session checking it out on various instruments with different mics.
I love the precision and fatness of the sound - different to all my other 500 pres, but in a positive way.