hard to argue, i have my experience you have yours
for me +15 is enough for m+ as higher is just for flexing and on that lvl healing does still matter
about "slightly better aoe dps" and burst capability its like you say atm but if we take doom winds into consideration and fact that WF can proc from earth shatter and crash lightning, things may be interesting (obviously blizz can cut that if we go to high but will see)
but it happens and i saved couple keys with it ;P
about rest yea ok everyone bring something to the table we bring WF totem to although what value it really have no one currently knows
http://www.simulationcraft.org/reports/PR_Raid.html
a bit to early to use wol sadly
maybe after weekend