Gonna give ya an obnoxious wall of text since I just went through pretty much what you're doing, except my resto experiment was with the arena build instead of full resto. This is just my experience and yours may be exactly the opposite based on that and pretty much every other factor there is. : )
About a week ago I spec'd the arena build: 1) For variety to see if I liked it, 2) To see if I could be leet in arena so I could farm arena points faster to boost my feral gear, and 3) To give my guild healers a chance to play their alts.
I'd been good about collecting healing gear, so after picking up the PvP rep blues I had TWO healing sets: PvE including 2 pieces of Moonglade, plus
Ravenwing Pauldrons and a druidic helm I can't remember off the top of my head, and a PvP set including three of the kodohide rep pieces plus some other stuff with healing but focused more on stam and resilience. My gear was nothing special but wasn't bad for a fresh respec. +1100 heals and 300 regen in my pve set and +800 heal with 190 resilience in my pvp set.
Based on my experience and your "I miss tanking..." comment one day in, my guess is that unless you find a good group to roll with on a regular basis, for arena and/or PvE, or are willing to spend a lot of time in non-heroic instances and/or being very helpful in battlegrounds, resto's gonna get old real quick.
I missed tanking right away, too. I couldn't stand being "weak" in my spec'd role when I'm strong at melee dps and tanking in my 'real' gear and spec. As resto I emergency healed one heroic fairly well when a guild group's healer bailed (didn't kill last boss cuz tank couldn't hold aggro, but other than that I was clearly geared and skilled for it) and was very effective in BGs, but I SUCKED in arena even with the supposedly OP spec and wasn't confident enough to sign on as a healer for heroics. I'm always antsy to gear up via badges and heroic drops, so being relegated to non-heroic instances would suck for me.
By far the biggest thing for me ended up being exactly what Jackofroses led off with "if you miss tanking than why don't you stick with it?" I just like being feral druid bestest of all and wasn't having as much fun healing. Also wasn't as valuable to my guild as a non-heroic healer as am a heroic/kara-capable dps or tank. I gave it a go and I now have better gear to respec back to it if my guild needs me to for a run or week or something, but I am convinced that I am forever feral.
So I respec'd BACK to feral last night, and omg clicking "Mangle" in the talent tree put a SERIOUS smile on my face. The poor deer and squirrels in Darnassus didn't know what hit 'em! Can't wait to go bust out some dailies by slicing through mobs again, or to tank a heroic. WWWWeeeeeeee!!!