I doubt you'd see any difference in performance either UNLESS you have percolation issues.. Then, I think the shield would help a great deal. I use one only for this reason and I believe it's easily worth it's weight in help..
They come with a thick 3/16"gasket which also helps prevent heat transfer, but is really there to provide clearance for the 30cc accelerator pumps.. FWIW, using two gaskets is required if you have a 50cc pump, but at WOT, the pump arm may still just touch the shield. ..and yes, be careful tightening the carb nuts. I progressively tighten them in a diagonal sequence.
OER who are providing repro of this shield are stapling the heavy 3/16" gasket to the underside of the shield which is incorrect.. I assume this is a mis-communication between English and Chinese and lack of quality control.