Okay so I don't have a pally but have a question (or two) for you all.
I was tanking steamvaults last night and had a level 69 holy pally doing the healing on me.
The problem I had was that the pally was a bit inconsistent in healing behaviour and was pulling a lot of agro off me. We didnt have a lot of cc (or the cc would break frequently) and so I'd pull beginning to tank the main target and in the two seconds of doing the pull the 2nd target to dps (despite doing a growl and ff on him) would peel off and go straight to the pally.
Normally after the first few seconds I would switch targets onto the 2nd dps and get a few lacerates in, but the threat grab to this pally was so quick.
I have had no troubles with pally healers before - in fact my opinion (other than this one last night) is that pally healers are the greatest - for mana efficiency and survivability.
Why was this pally getting agro so fast? Normally I would have though it was due to heals being too much, but to be honest he was barely healing me. I'd get random 900 heals but not a lot. And he did say he was holy (though I never double checked armory).
Also when he did get agro he died so quickly - 2 or 3 shot, which is very unfortunate if I am feared or stunned/dazed at the time. I checked his clothes, most of it was plate with only 1 or 2 pieces of cloth.