anyone tried tanking with ret paladin (3.0)?

I think there are a number of others who run the prot pally + resto shammy + 3 ele shammy combo (or 4 ele shammy), has anyone tried running their paladin as ret in heroics or even PVP? I'm going to try that later this week, just getting used to all the new spells first and wanted to do some regular raids (as prot) before I respec my pally.

I'm updating addons still, no play time other than throwing on a build. My spell power went up from ~180ish to 430ish so I'm not quite sure where that sits things. If things aren't going great, it might be something to try. I don't think a ret spec would hold up to all that damage though.