Flexy like a noodle? Would they have been the weakest link on the bike? What do you weigh?
"But, do those "pin/ramps to facilitate shifting" get in the way of fixed gear use?"
No.
And removal of the rings is fine, add correct ring bolts ($7) and get the chainline straight.
My RD's shipped today. I go 240# on a good day - I'll let you know if they flex or not.