Caster trinket for prot pally?

Ok, to put it out ive been lazy and never farmed bh rep for the "pvp" mastry/resistance trinket and am still using a Porcelain crab (346 rare - 280 dodge a chunk of mastery on hit proc) as my avoidance/mastery trinket, and was considering swaping it for the valor vendors Soul cascet caster trinket (320 mastery, useless spellpower on use). A reforged crab gives about 170 dodge/110 mastery, so the 200ish mastery difference would increase my block in 2.5%, with the downside of losing a "unhittable" with 10%ish uptime from the crab proc.
thoughts? anyone else ever looked at that caster trinket with greedy mastery eyes?

Yeah thought crossed my mine, I have but opted for the http://www.wowhead.com/item=68713; didn't really take too long to grind it out and it's worth it - suck it up and grind for a week. Shorter if you all control BH a lot since you can get up to 12 additional dailies. Since I'm Alchemist I have http://www.wowhead.com/item=58483.

On my DK I have the BH Mastery trinket and I madehttp://www.wowhead.com/item=62048 since I had made most of the cards and the ones I was missing were cheap - I actually like that DM trinket - I know conventional wisdom is it sucks, but I like it so far.

I used to think the crab and finger trinks were BIS 346 gear. Then I found Tia's Grace. It has almost as much Mastery as the TB trink and the Agi stacking proc is guaranteed, so you get around 1% more dodge. It worked out to be the equivalent to the Mastery from the TB trink.

So the TB trink is what you want, but in the meantime, Tia's Grace is a worthy alternative. IMO, it's way better than the Crab trink.

i alweys beleived the finger was a horrible trinket. parry and a on parry dodge proc, right? both subject to DR, low chance to proc unless tanking a horde of mobs. id consider stonecores stam/armor proc trinket (or tje JC stam trinekt) a better 346 over either, unless your considering only avoidance trinkets.
Tias is a nice tip though, i might go get that one. though will all my spare VPs, i think ill buy soul cascet too.