Easy outs, yea right, better label is 'how to make a PIA job a Major PIA job'. Thankfully I gave my last easy out kit away to a neighbor kid to use on his VW which might have been a mistake, his parents are customers of mine but I did warn him in front of both of them, several times but he was determined. May haps I should have had him sign a wavier... did warn him that I would shoot him if I caught him bringing them back...
I broke a big one removing a broken bumper bolt on the YJ last year, that sob took me over 3 hours to drill out and that was sitting on a empty 5 gallon bucket, steady supply of coffee, can't imagine having to do it from underneath. I actually got into the habit of taking those nutplate bolts out yearly, one at a time, just to clean them and re antiseize them and it still is a fight every time....
I have actually thought about using one of those squirt type oil cans, the half pint ones, to squirt oil, atf, holy water or SOMETHING in there, in liberal amounts, every time I change the oil and do a grease job...
As for removal of the broken easy out, buy 5 good bits, 1/2 drill, one of those oil squirt cans and get comfortable under there with a nice face mask, go slow and lube it good...
As for replacing with grade 8's, sheesh, grade 5's are bad enough to drill, can't imagine if EVERY bolt was the hardness of an easy out...