Controlling the Arranger from a Midi Guitar

I would like to get the Arranger "backup band " to follow the guitar chord changes I play. I tried in the store (Guitar Center in San Jose, CA) to get Parker Midi guitar to control Roland EM2000 arranger. Store people after an hour of trying were not able to make it working. They told me that the only keyboard that can do this is Solton X1, but never had this model in the store.

Did anybody tried to do this?
Is X1 really capable of doing waht I want?
What combination of a guitar and keyboard works best?
What is the best place to buy Solton X1?
When the newer version of X1 is due?

Thanks

hi,
i have an "old" GR9 Roland Midi guitar controller, and i use it with a i40M Korg : it's really great and easy! i40m is an arranger module ( no keyboard) and it has a special configuration to be controlled via midi guitar.
by the way i tried my gr9 with an old pro-E roland arranger, and it works great too... http://www.ifrance.com/techno-id