anytime you use Heavy Shot or Straight Shot while using WM it will cause you to suffer a DPS-loss. if Heavy Shot and/or Straight Shot are the only things left for you to do... disable WM. however, Straighter Shot is different. any instant attack will only benefit from the raw 30% boost to damage. and you should also always try to apply your DoT while using WM.
this is what i do. it may not be the best way to do things, but it works well for me.
Area of Effect, when there are 3 or more targets...
apply Straight Shot then DoT to at least one target. use WM exclusive actions. use a damage buff then use an AoE attack. depending on enemy health, refresh your DoT as needed. depending on enemy health, apply DoT to the highest HP enemy and continue with AoE again. don't forget to throw out an Empyreal Arrow or two.
Area of Effect attacks, when there are only 2 targets...
apply Straight Shot then apply DoT to both targets. use your WM exclusive actions. if needed, refresh DoT before exiting WM. use AoE until one enemy remains. if you choose to go back to WM for something like Empyreal Arrow, then stay back on single target damage, and if HP remaining is enough use a damage buff too.
i think people are estimating that auto-attack potency to be around 80~100 potency. if it is close 100potency then it makes things easier to add up. so if 100potency is true and we look at using WM to AoE with exactly 3 targets, then we can see there is zero damage gain. basically what will happen is that your auto-attack will just get divided in to 3 parts which will be evenly divided among the 3 enemies. so same damage, just it is placed differently. with 2 targets and WM on, we loose roughly 30% of our auto-attack in damage.
for single target damage...
i make sure the WM in ready for removal. enter combat with it already applied. so i...
|indicates| an action that is not on the global cooldown. (indicates) an action that you may want to save for a specific moment in the encounter.
Straight Shot>|Bloodletter|>Wind Bite>|(Blunt Arrow)|>Venomous Bite>|Empyreal Arrow|>|WM|>>>Heavy/Straight Shot>|Repelling Shot|>and any Bloodletters and Straighter Shots>>>|Blood for Blood|>|WM|>Iron Jaws>|(Barrage)|>|Empyreal Arrow|>|(Sidewinder)|>>>Heavy/Straight Shot and any Bloodletters and Straighter Shots.
basically that, rinse and repeat. where Blood for Blood was used i would just use another buff. next time for me would be Internal Release then Hawk's Eye. by time getting around to Raging Strike, Sidewinder will be ready again. after that, Blood for Blood will be ready again. another thing to note is to try to refresh Straight Shot before re-entering WM.
anyhow, that is just my take on a play-style for BRD. by playing like this, i have been able to notice a rather good increase to damage output as opposed to staying in WM 100% of the time.