CNC Welding

Hi,

Just wondering if anyone has experience with MIG welding with a
gantry style CNC system.

I am wanting to set up a MIG on my profile cutting table - 3500mm x
2000mm. I am wanting to know possible pit falls to look out for, and
any 'lower' cost solutions for interfacing and sensing the weld.

I will be buying a new MIG for this job and am getting bombarded
with facts and figures about the different types of machines
available, some of the top self units can be ordered with a robot
interface board. Are these absolutly necessary or can the job be
done successfully without interface boards($$$$).

I will be welding 10mm mild steel plate in long straight runs about
2000mm long.

Any help people can offer would be greatly appreciated.
Thanks.

Andrew