Okay, so here is the bar with 200# on it. Definitely is flexing, but seemed pretty darn solid still. I was nervous to put on more weight as I didn't want to do any destructive testing. I don't think I'll be sniffing 200# anytime soon with this thing (if at all).
Next time maybe I load the 55# plate onto the double-walled section (just need to slide it over 1"-2"). That would probably help since how I designed this thing the weights hang on single-walled tube. I really wish the shipping on tube over 58" wasn't so dang expensive. I would've double-walled the entire bar and then gotten 1.75" diameter 1" pieces for the band holders and just glued those over the double walled tubing. Oh well. I didn't think I would be using these weights actually after seeing how people struggled with 106# on this video: http://www.youtube.com/watch?v=yWybDN10WJw. I think their design definitely flexes more than mine at lower weight but can withstand 600#!!! Crazy. I almost think a solid 1.25" rod sleeved inside a 1.5" tube might be too rigid and not give the intended effect.
Maybe I'll get a 12" 1.75" diameter sleeve to put over the existing band holders and then get 2" diameter 1" pieces. That would solve my single wall setup. Or slip a couple of feet of 1" solid rod on the inside... Even easier!