1 less ret. Your burst suffers. I think you might have problem killing people. With that said, if you run with a offensive healer (disc priest, shaman). Then I think it will work. Defensive healer won't work IMO. pally healer (no way). druid (probably not, cyclone is good, but no purge).

I tried this briefly with a druid. dk + 3 paladins + 1 druid. My druid healer got zerged while I was just boucing around in CCs. I am not very geared, but it showed a trend. People are all running around with 30k hp nowadays. No purge, no heailng debuff, no bloodlust, you are not killing anyone.

Overall, adding 1 healer didn't improve my survial much since he is zerged first. And my chances of killing someone drops a nouch due to 1 less dps.