I bought a standard 155 and put Fox shocks from Carl's Performance all around. I did this because I wanted shocks that will perform in the manner that I will be using them, not the broad spectrum of riding styles the factory sets up a sled's suspension with. Also, I'm outside of the "average rider" weight, height, pretty much everything lol, so I needed to re-do the shocks regardless, so why spend extra money for the nicer shocks on a pro when I have to take them off and have them rebuilt to my liking anyway? If you are in a similar case, then yeah, go ahead and buy the standard and stick nicer shocks on it.
I like the standard for its extra cooling capacity and it's pivoting riser on the steering post, I've always preferred that style--easier to work on and adjust. The only thing I would change is build a standard 163", since I'm a bigger guy, I would like a little more track I guess.
All in all, there are perfectly good reasons to buy the standard and stick a little money into it, and there are perfectly good reasons to just buy the Pro version. Either way, great sled.