Aside from a few modest design mods (mostly superficial) and the additional functionality possible with the throttle display (which I totally have no use for), the most significant change was supposed to be a different and improved type of contacts that would make the Pro more durable.
Having gone thru seven (yes I said 7), X52's in just over two years, I purchased the Pro hoping the promised improvement would pan out. It didn't. Three months of use and it's sitting (with a couple of the older X52's) waiting for me to ship it back to Saitek for replacement. I've had one actually replaced by Saitek. It's the one I'm using now and it's porked as well.
Aside from my very first X52 (which went 10 months), I have yet for ANY other X52 last longer than 3 months (and ofetn much less) before becoming unplayable.
Under regular circumstances I would never buy from such a company after the third defective product. However, I'm caught by circumstances in that when it works, I love using the stick. I can't use CH because I am physicall unable to use rudder pedals, so need a twisty stick. And finally, I haven't found any other manufacture's product that works better AND that I enjoy using.
I simply have to get off the dime and start rotating my stock of X52's back to Saitek for replacement, unless someone has a better suggestion.