Elemental damage makes a difference the higher power you are. The reason being that they are a % rather than a flat amount. If you want to preserve some critical and injury if you value them, then reforge all the stats besides that. A little bit of life is not that much value even if the BP does decrease.

Since you can increase 20% of each element resistance, it's way better then just raw power. And you got 6 slots in tool, so you can keep injury/critical, as suggested above.

In the past when +4 elemental resistances were available used to be better to go for a full set of them than secondary stats, but with the current ones, limited at +2, I'm no more sure.

100 damage reduction is almost granted to be better.

I'm pretty sure I managed to get a +4 water elemental resistance stat on a recent piece of equipment I earned from TI, but for damage reduction, I heard it only affects the damage you cause to yourself while under the chaos status?