at lower levels, the only difference is how many resil points give you 1% damage reduction.
i am pretty sure that now with 40% base resil added in, resil follows a non-linear return (not just nonlinear, but something with an increasing derivative) at any level.
for example, look at this druid's resil percentage.
resil still works the same way it does where it's less beneficial after a certain point because it has DRs
here's some math i did in literally 30 seconds
your druid: 41.43% damage reduction, 780 resil = .053115% damage reduction per point of resilience
my priest: http://us.battle.net/wow/en/character/sargeras/Snipemasterx/advanced
36.54% damage reduction, 663 resil = .055113% damage reduction per point of resilience
my mage: http://us.battle.net/wow/en/character/sargeras/Anatomyxxmd/advanced
28.10% damage reduction, 481 resil = .058420% damage reduction per point of resilience
it doesn't take a genius to figure out from those numbers alone that resilience gets worse as the number gets higher, hence why stamina is better after a certain point because you'll effectively gain more survivability by having a good mix of the two rather than gemming purely in one or the other
edit: First post I used level 90 numbers.
With zero resil, your EH is 1/(1-.4)=1.6667 times what it would be in PvE
If you have extra 41.43% more resil from 780, then your EH is 1/(1-.4-.4143)=5.11 times the PvE number. 5.11/1.667=3.06, a 206.6% improvement. 206.6/780 = .265% per point of resil.
Using 28.1% and 481 resil. 1/(1-.4-.281)=3.135. 3.135/1.66 = 1.881, a 88.1% improvement. 88.1%/481 = 0.183% of TTL (on average) from each point of resil.
.264 is much larger than .188. Those are called increasing returns.