Re: griffon question
You usually seek the -eLR, because it greatly increases damage to originally immune monsters which were broken by Conviction aura or Lower Resistance curse. Both of them work with 1/5 efficiency against LIs, which leaves them with relatively high LR that can be further reduced by the -eLR mod.
Example:
Slvl12 conviction aura from 'Infinity' lowers their resistance by 85/5=17%, which leads to:
17% of your base damage done vs monsters with 100%LR
12% damage to 105% LIs
7% damage to 110% LIs
The -20% eLR from perfect Griffon's takes these to 37%, 32%, and 27% respectively, which represents a massive increase. For Lower Resistance charges, the difference is even bigger.
The +%light damage on Griffon's is still quite useful for amazons, since it multiplies your base damage (the same way sorcie's Lightning Mastery does). This is also a reason why for a sorceress this mod is of little value (it's added to the mastery percentage).