I have the Tankstick + trackball, It is ok and does its job. I do think now that I have leaned more about arcade controls I would build my own next time. I do like the layout.
Another thing i learned is that the default encoder on the tankstick has a 6 or 7 simultaneous button press limit, not a huge issue unless you are into two player fighting games.
I have a bit of experience building/modding sticks and I have to add that ANYTHING X-Arcade makes will be basement quality knock-off buttons/sticks. Also just look at the button layout on any of their sticks, its a straight line across which is terrible, ergonomically-speaking.
You will need to gut the entire stick and put a new encoder (you can buy Zero Delay encoders on ebay for like 10 bucks a piece) and new sticks/buttons if you want an arcade-quality stick.
edit: here's everything you need to know about X-Arcade trash. http://forums.shoryuken.com/discussion/193131/the-x-arcade-arcade-controllers-thread
My suggestion is either the Atrox (its really expensive but at least made to be modded easily) or anything with Sanwa/Seimitsu parts. Madcatz puts real parts in their sticks which is nice.
i think the X-Arcade Dual Joystick and X-Arcade Tankstick + Trackball are the best choices from this list if you want option for 2 players, have the space for it, want to be able to replace buttons/joysticks easily and want compatibility with retro and current gen gaming consoles via adapters. A review of the X-Arcade Dualjoystick and Tankstic + Trackball are available on youtube, CGR did a good summary and the product video on x-arcade's website does a great job of displaying the features of these arcade fighting gamepad controllers.
I have the X-Arcade Tankstick on my MAME machine and it's awesome, they say it's unbreakable and I've put that to the test, my friends and I just button mash and rip the joystick all over the place madness style many times and it's a real beast, still looks and feels mint after nearly 2 years now :D