yes dex does matter to any caster or meleer. Dex on a caster either helps u to cast through getting hit or if you are disrupted it tells you right away more often instead of casting the whole spell just to get the u've been disrupted message. On a side note if someone got real daring they could up their dex to near 200 and then get the earthquake rod ;-). A definite sight to be seen. Seeing as though dex effects how often you proc and how often you hit.
regarding dex helping channeling and stuff, i doubt it. i've never heard that stated before.
hierophants crook is fun for farming greenies. just get a focus before you go out, and your dex will be plenty high... then run around and tag everything you want and stop and whack at them until it procs. or if you ever have the chance to join an AE group adventure, ask the chanter (if they dont mind) to werewolf you. +100 dex for 6 minutes (or longer with duration enhancements)... then you whack at the mobs between upheavals and hopefully it procs once or twice.
Ok, finally a high level druid loot that's worth the effort.
This fits what high level druid armor really should be. Low Weight (as leather armor SHOULD be) AC, Great Wis for hands to free up other slots for Resist/Mana gear. Some HP, good extra mana and a bit of resists. The effect is nice too if its rechargeable, still nice to have a dispell handy since you don't often have it memmed. I don't know what the 10 dex would be good for since druids don't ever need it but its not going to hurt you either.
I'd been getting disappointed with the crappy stats on the other Twisted Nature pieces and assumed all of it would suck, I'm glad to be wrong on at least one piece.