Tige and Centurion have great reputations for surfing and for 50k you will be able to find something very nice.
I agree with brett that if he can pay a bit more, the MB 23' would be a great boat. wakeboarding wake is real nice and have heard the surf wave can be really good too. sounds like he will finance, and interest rates are usually better when buying new. So he can pay more for new and have a similar payment. worth a look.
If we are talking new there are some great options for 50k in the 21-22 foot range. One is an Axis A22 that you can get for 50k, and the swimstep that is new in late 2011 is surf friendly. chattwake has a nice surf set up on his 2011 that he just sold, should find some pics on here somewhere. Surfers here really seem to love the centurions and tiges... I would go that way.
As for the x30 and lsv247 as originally asked... i can comment on the lsv247 only. My buddy has an 08. Its beautiful, huge, surf wake is really big on both port and starboard sides. I am not a surfer, and have little experience surfing behind boats (old tige, x45, 247 only). It was fun and had a nice pocket. the wakeboarding wake is great, its a malibu. with full stock ballast 1250 and wedge, it was really nice.
I vote for the malibu