The other reason i dont like long and wide for that matter Fixed gantry, is that the table that moves has to ve sturdy and the only solution there is a very expensive aluminum plate, while you can throw anything you have at hand for the bed . Also a protection should be done for the ballscrews

And as the table grows, the motors will grow and the machine will grow slower.

Not a problem though if you will be cutting metal mainly

I still believe the Z is the most important thing, not only the gantry , if gantry properly made. And i can prove it to anybody how a 2 meter wide gantry cuts up to mild steel with mirror like finish. And aluminum like butter.