Yeah, less melee would certainly help. My guild runs a 2 tank, 2 melee, 2 heals, 4 range set up for this fight (well, when we were progressing). Now we can take more melee since we've got practice on the tactics. Alright, let's see if I can explain...
Oh, I play paladin tank, and the other person plays paladin tank as well. So that's our tank set up. We've heard a pali/warrior set up would work better, but this works for us. We use our divine sacrifice on blistering colds, by the way. And then when that's on cooldown, use hand of sacrifice on key players that have problems with damage.
range and healers stack at top middle of stairs. Sindragosa is at the bottom of the stairs, head facing to the right, looking down the stairs. There is probably a good consecration length between the bottom of the stairs and where the melee stand.
1 tank takes it first (just like the majority of the fight) and the other stands with melee.
our first ice block goes to the left, facing down the stairs. This isn't random choice, it has to do with this being the easiest way to tank switch.
this first iceblock is the one everyone uses to drop their stacks. wait a few seconds, then dps it down. Heals/range return to top middle, melee return to sitting on Sin's butt.
second ice block goes to the right. (alternate every single ice block no matter what). call out your iceblocks. have one person call them out. this iceblock is dps'd right away. if you can drop your stack, great, but not as much need if your healers are good. use the left iceblock to drop stacks.
i was always the second tank, the one who started in the melee zone. i would participate in 2 iceblocks, then usually we would switch. So I'd do left, then go back to melee, right (drop stacks too), and take over as tank. Other tank would get ready to go to the left iceblock and drop their stacks, then go melee, and do the right iceblock. He and I could go 3 or 4 iceblocks without switching, but I'm not sure what the gear level would be comparatively.
honestly, the key to this fight is having someone call out, at least til people get into the habit and muscle memory of the fight. Took us a while, but it's really fun when you get it!
It's kinda like the safety dance. People just need to know where to go, and when to go.
I hope that helps, and I hope I didn't forget anything.