Straight haste dps gear vs. tank gear reforged to haste?

Hi all,
I'm an off-tank for a raiding guild and recently they advised me to go from a dodge/parry build to a straight haste build using ret plate. We did up to Durumu last night in ToT, and I noticed my GC procs per minute were MUCH LOWER, to the point I couldn't actively mitigate a lot of the time. Before I'd say I had a proc every 5 seconds, now it's closer to 8/9/10 seconds before I get a new proc. I think part of the problem here is that the tank I replaced around 5.2 was a pre-5.2 haste protection paladin and thus his style of build worked when it was 20% vs 12% proc rate and so my guild remembers the heyday of haste protection paladins, whereas now I'm wondering if I need a mix of parry/dodge plate reforged to haste and dps plate to make this build workable.

Does anyone have any suggestions? My character is Zopah on StormscaleEU. As you can see, I've gemmed haste hardcore, but I died 5/6 times in total, even on successful boss kills. I do wonder if perhaps my stam needs to be stacked, and I'm currently working on getting some haste trinkets, although I'm not sure that's ideal either.

Many thanks,
Zopar

Welcome to the forum
First off you should hard cap exp 15%, hit and exp are our best damge spike reduction stats.
I can't remember the numbers they'll be in Thecks Matlab thread somewhere (on phone hard to search) but even last patch GC procs where a relatively small amount of our holy power generation, single target haste will increase your holy power generation much more than avoidance, even though there will be less GC procs the lower cd on CS and J will more than make up for it.

If you're dieing a lot you should try to find out what caused those deaths.
No cd up for a big magic hit, miss timed SotR for Triple Puncture, no healing for 5-10 sec, standing in bad shit?
More stam will give you more margin for error with all of that so probably a good idea to pick up a stam trinket and/or more gems.
Basically haste is still good but you need hit and exp caps plus a well executed rotation to make it work.
Gl in ToT

You should gem for socket bonuses (except crit in belt). Missing out on 270 stam in helm just hurts . Also for progression you should consider gemming stamina, if you are 25man maybe even try the 150stam armor kits for boots and gloves.

edit: also put 200stam enchant on cloak
Just for reference (i'm OS tank) when I tanked lei shen I was at ~620k hp unbuff and I still felt like I was cutting it pretty close.