If you can manage your DPS and heals at once, you'll be a hard to kill three-some.

Earth Shield on the squishier healer.
Nature's Swiftness twice.
Lots of HoTs, Swiftmend, Wild Growth, Chain Heal, Direct Heals, etc.
Totems, ManaTide/Innervate, B.Rez etc.

Will a single warrior be able to dps/kill, with only limited healer dps support?
Three on one, or three on two should be ok.
How will you do, three (you) vs three or more?

If you want to try it, go for it.