I ride the underground 122 it's a really good board, great pop for jumps, really good flex for snappy turns but the only downfall is that when the wind is light, like under 12 knots its hard to get up & going. You need something a bit stiffer for lighter winds. I have a slingshot sx132 also and if i have trouble getting going with the Underground 122 in lighter winds i use this board and i have no probs. I havent tried the 132 underground yet so i don't know if i could use that in lighter winds. I'd like to compare it with the slingshot as the slingshot is a stiffer board. Anyway imo i give the Underground 122 an 8 out of 10, but thats just me.

the North jamie pro 05 M supper flexi but but also a bit hard to time the pop but when you do you up in the air like superman but not so good in light winds

Just about to mention the ADDICTION boards - we tried a proto, sent courtesy of the gents from WA and it was a top board. Loads of FLEX.

If you have a few boards get one of those, your new secret weapon.

Hi Caution
Yes the boards flex so you don't get the jarring ride but at the same time this helps to keep the rail in the water much like a shocker on a car rather than bouncing and skipping.
Yes the boards do change shape create drag and slow you down, but this happens when you load them up and edge hard usually when you are trying to slow down or are overpowered. When you are riding fast you don't edge hard the board is riding a lot flatter so it holds it shape.
Try one out

Cheers
Pete

www.addictionkiteboards.com