There's a familiar theme - "Are you ever going to actually make anything?" "Well, as soon as I've finished this machine to make that tool to finish off those other bits I started a year ago last Christmas, I'll be ready to go..." OTOH, I have been able to respond to the "I need a turntable to display my embroidery in an exhibition. It has to do about 3RPM, it's Friday evening, and I need it ready and painted for Monday morning" kind of request so I just about keep my head above water re brownie points.
I know about wood bending - my current router is an MDF build (cold-rolled cow dung, as a friend unkindly called it), and you can judge the humidity in the garage by the sag in the bed. And the Z platform. And the gantry. I'm about to stiffen the bed with a couple of bits of steel tube I recently found, although given that the bed currently has the stiffness of crocheted cooked spaghetti, that won't be too difficult.
There are a number of build threads on this forum where people have gone to considerable lengths to build a really strong machine, and I have to agree that a machine that is a bit too strong is a much better result than a machine that is a bit too bendy. However, it's difficult to know where "acceptable" is on that kind of scale, which is why seeing some measured numbers helps. Is your machine currently usable? Can you relate the stiffness numbers you have obtained to actual cutting speed, DOC, surface finish, etc, results?