I can't vouch for the Challenger and wake surfing, but I finally bought my 230 Wake this spring. We have been experimenting with weight and the factory ballast system. Here is what I have found. The factory ballast system is enough to wake surf with even without a lot of people aboard, we've done it with a driver and spotter. The wave is big but short, the "sweet spot" is small, right behind the boat and hard to stay in. Of course if you add more people on the surfers side it gets better.
I bought a pump and a plug and filled the ski locker about 3/4 full of water. What a difference!!! The wake got much longer and so it was easier to surf. I am going to purchase a 540lb capacity fat sac for in the locker for next season because filling it 3/4 full eventually drains some of the water out over the top of the ski locker, (no big deal the bilge pump will pump out the excess) but the wave length diminishes quickly. I am also adding a 300lb ballast that will fit into the storage compartment which sits above the engines.
I am VERY pleased with the 230 Wake's surfing capabilities. The wake is not as "clean" as you get from inboards but at $20-$30,000 less for a comparably powered and sized inboard...I am extremely happy with my decision.