I have had XTRSense since at least last June and love it, recently I thought I would try GSB to see what the praise was all about, I was not impressed. The phone ran way worse, all kinds of force closes, it was a lot slower, and had no advantages over XTRSense.
I tried GSB for about 2 weeks and gladly went back to XTRSense. On XTRSense the eris runs flawless.
Did you reformat your SD card and do a factory restall when you flashed GSB? That made a HUGE difference for me.
So saying stock has gains over the current state of ROMs is based on as much experience as one can have in this arena and really saying a lot. I've probably flashed 30-40 times now.

a fresh stock rom runs fine. but the more apps i add,and the more time goes by,the more confused it seems to get.
youre only a nand away from where you are if it doesnt work out 