In my experience vegetal aromas and flavors are extracted much more noticeably at lower temps. If I dry hop with american hops at 55 degrees (winter in my cellar), I get up to several weeks of grass/wood before it dissapates. When I dry hop with the same volumes at 70F, it only typically imparts that character for a few days.
And yes, you're reading that right... I get chlorophyll notes at the BEGINNING of dry hopping-- not after extended periods of dry hop contact like prevailing opinion tells us.
I almost always dry hop cold and have never noticed any unwanted vegetal aromas and flavors. I'll have to try your method on my next IPA and see if I can tell the difference.
I used to dry hop in the keg cold. I don't anymore. I didn't really notice vegetal, grassy favors when doing this at first, but lately it's really come through and I don't like it at all. I noticed it most when using columbus and other C-hops and that's when decided not to do it anymore. Now I will either throw them into the primary after fermentation, or transfer to secondary. In both instances dry hopping is at room temp and I cold crash before kegging.