I have a freak, but have used a JT two piece which was very nice... also....
The main thing to think about when getting a barrel is the paint your going to use, and lengths you want... if you go for a freak (or wait as rumour has it others are working on similar systems which may drive the price down a bit) it is basically in three pieces the back piece which screws into your marker, the inserts, which come in different sizes, and allow you to get a perfect paint to barrel match, and the fronts which come in different sizes..
Okay the are quite expensive, but when you think if you go with a solid barrel you will be hard pushed to get a good paint to barrel match everytime...