Your swing speed doesn't really matter when it comes to the ProV1 or the ProV1x's. You need to play the ball that caters to what you want it to do. If you're looking for more distance and less spin, go with the ProV1x. The ProV1 is supposed to have more spin and a little better control around the green.

Joel,

It all depends on each player. I would suggest either doing a ball fitting or just get a sleeve of each and play "best ball" or "worst ball" for a few rounds playing one of each ( a Pro V1 and a Pro V1x). See which one you like best. Feel will be a little different, performance in the wind a little different, if you play on firm conditions one may suit the course better, etc.

"Best ball" and "Worst ball" are the following. hit two shots (one with a ProV1 and one with a ProV1x) and either take the best result and then play two shots from there (or take the worst and play two shots from there). Or shake it up. You want to test each ball in each facet of the game, drives, fairway woods, hybrids, irons (short, mid and long), into wind, down wind, chipping, putting, etc.

There are tradeoffs for each ball but they both are great and I am sure you will find the best ball for you and the conditions you play on most.

Feel free to ask any questions and good luck. 

Michael Breed had some great stuff regarding golf ball selection on The Golf Fix Monday night. The take away was...what are you doing with your game and what ball is going to help you score better. It was a short bit but it is food for thought! Play well!

Swing speed is not the biggest factor when determining which ball to use. I recently took part in a Titleist ball fitting and I can't recommend getting a fitting done enough!

All the Titleist guys were more than helpful, especially my fitter David Bustamante. Hitting balls in front of a Trackman provides you with so much information about your swing. It's almost unreal how much detail it can catch. 

We were able to determine, due to my spin rate on full shots, that the Pro V1x is the choice for me. 

If your club or a local club is offering a Titleist ball fitting, go sign up. Well worth it. 

try the pro v1.