Yes I did compare the flexing at the hardware store between them, and rigid does not flex at all compared to EMT. I edited the above post to show the chart comparison between them both.
Why would this not even be in the ball park of working? I am not proposing to making the gantry out of this this heavier material, only the frame that supports the gantry.
Thanks you for your fast responses to these posts! I am just thinking out loud here to see if this might be an option.