Pro4 is better but very little difference, and the pro3 is $20 cheaper. The second one you listed has bad reviews on newegg, always buy products with 4+ eggs. I personally own the Pro3 and like it, as long as you don't crossfire.
don't get pro4 if you're crossfiring, the entire pro line only has one pcie 3.0 x16, so the performance will take a hit when using the slower slot. Get something from the Extreme series like extreme3 or extreme4, depending on budget.
This one has 2 pcie x16 slots but when you plug two graphics cards in those slots the slots will work at x8 speeds. This is the problem with all low cost motherboard. Both the slots share the same bandwidth.
That is not a bad motherboard, but MSI motherboard have been receiving a lot of complains lately.
I won't say MSI is bad based on what people are saying until I find something wrong with it myself or find bad reviews from several reputed reviewers.