Quote Originally Posted by jarjar View Post
I can see how this would be problematic if you want to mill on the side of long pieces that won't fit under the gantry. With a fixed bed the cutout allows the work piece to extend below the bed. If OP wants to do a lot of those pieces then the moving gantry seems indeed the way to go.
Pro's and cons to both but IMO the cons for having the slightly longer length end machining the price is a too high price to pay in strength terms. There are other better ways. . . For instance.!

For high clearance requirements, I have a design that will work and provide high clearance under the gantry with minimal loss in strength. I've just built a small version with a cutting area of 500 x 500 x 350 that could easily have the clearance and strength increased if required without any impact to it's cutting ability.