BRD on healer for interrupts / harassment
MDPS + tank on their RDPS

I frankly find this to be optimal in 30/40; if the healer gets a SC+Raise off, BRD wheels to drop the raised player. In 30/40, most healers operate under the assumption they will be targeted first. BRD on healer maintains that illusion typically long enough to drop the RDPS. Once it's 4v3, dropping the healer becomes more feasible as your healer has a marked survivability advantage.

Frankly, dropping the tank would likely be the best option, but I've found that tanks in 30/40 are often the most experienced players. You get a lot of derp RDPS who die before they even realize the healer isn't being targeted.