I haven't used the MXI X58 Pro, but have had considerable experience with THREE different MXI X58 Eclipse, and soon will play around with an MSI X58 Platinum. I've also read about other people's experiences, and have read every review I can find on them.
If you aren't overclocking and aren't going to be running fast "enthusiast" RAM, then they will work fine.
While they are improving with every BIOS release, RAM support still isn't as good as the Asus P6T or the Intel X58SO, both of which I've also used. With those two boards, "enthusiast" 1600MHz RAM just plain works. Set it to specified settings (or enable XMP) and voila! With the MSI board... :| Also, overclocking isn't as good. The Asus P6T was able to clock my 965 test chip to 4GHz easy on stock voltage. None of the three MSI has been able to do that. Closest I've gotten was 3.87GHz with vCore and vQPI boosts.
CPU at stock speeds and RAM left on AUTO (which clocked itself to 1067MHz) the MSI boards ran just fine.
That being said, with the "right" RAM I've gotten 1600MHz memory at the 3.87GHz processor overclock and it was stable. I just wasn't able to get more while the Asus went higher with ZERO effort. Also, BIOSes keep improving. On initial BIOS 1.23 I was only able to barely hit 3.5GHz overclock on a 3.2GHz CPU. On BIOS 1.32 I was able to hit around 3.6GHz+. Now on BIOS 1.42b (beta?) and can do the 3.87GHz. Thus, they are improving.