Thanks for that Toomast.
Fixed gantry looks an idea.
When I think of a fixed gantry, I automatically 'see' the gantry fixed across the narrowest axis requiring a very long bed travel, 4m in my case! If built correctly am I right in thinking that there is no reason I can't have the gantry spanning the longest axis? This way my machine would be a smidge over 2x2m allowing for a cutting area of 2x1 or thereabouts with the bed moving across the shorter axis.
It was thinking about the size of the machine which got me thinking about having the gantry move as the z axis (as per the video in your thread).