To compare FWD to RWD LSDs in like comparing apples to bananas. I agree 100% they work quite well in RWD, hell you can weld a RWD diff, and see awesome gains. Now if you weld a FWD diff............boom goes the diff and the tranny with it.
Your right I've never tried an EP diff....but if they use clutch like most others you are asking for problems. Have you ever had the clutch material wear down and go thru your trans? No? Give it time.
My lif experience with 60fts and LSDs
1st time ever yeah I had the same opinion as you-awesome and helped my 60 time. 1.88s consistantly 2002
the next year needed money and sold it, all other mods stayed the same, 60ft stayed the same........hrmmm. 2003
Got money and got another LSD, 60fts were slower 1.9s consistantly 2003
sold that one to buy slicks-60fts went to 1.75constistantly2004
late 04 got a G1 60s stayed the same, but the car "felt" better.
06-sold diff, and now run 1.6 60s, I did however upgrade my ENTIRE suspension
07 not LSD and cut 1.7s on street tires=no complete passes-tuning passes
I don't want to bash any vendors, but I have had all of them fail in one way or another, none of the damage was ever covered
, but they refreshed the diff for free.