I have an X-25, and we surf a lot. I fill up all the stock ballast and add a 750# fat sac + another sac as full as possible (about half full) to the rear compartment. I set center trim tab to 50% and 100% on the surf tabs. With a few people in the boat it makes a real nice wake. Or you can put another fat sac under/on the port seat. It seems to work best at about 10.5 mph.
Also, I would not buy the plug and play system. I don't think it's enough ballast. The storage compartments have more than enough room for added ballast in the X-25.
The wakeboarding wake is excellent with stock ballast.
You can't go wrong with the X-25 if you want to surf and wakeboard. It's a big boat and not very nimble around docks and tight spaces and naturally not too good for slalom skiing - I'm speaking as a previous ProStar 190 owner. It's very comfortable with 10 people in the boat and handles rough water well. We also spend a lot of time just swimming off the platform and we enjoy the flip up seats. I would say it's almost a perfect boat for me - if only we had a decent MC dealer in Oklahoma.