Dunno. Going out on a limb here, but starting with cold(er) water would give you a chance to at least get some maltase/dextrinase/glucanase/etc. activity going, wouldn't it? Not significant, since I think the temp. ranges for those enzymes are somewhat small. Plus, if you're not planning on pausing at those temperatures, it'd be a cursory step at most - as the temperature builds towards your 150+, those will start denaturing.
The unfortunate thing about non-amylase enzymes seems to be that they work best after amylase has had its way with the starches...which is opposite the way you'd wish it to work out if you're trying to be efficient and hit all the enzyme ranges on the way up.
Damn you, nature!!
So...in the end, I don't really think you'd get much of anything out of doing that.
Unless someone else knows of any potential benefits associated with steeping grains in cold water?
(1 last thought: one benefit I can think of for doing it the tried-and-true way of mashing after reaching your high temperature, is that adding grains to the hot water can help cool it back down. If you're heating your heating your water until it reaches desired temp., then it'll keep getting hotter even after you shut off your burner, right? So adding room-temp. grains will counter that and help keep you in your desired range. Maybe I'm just talking hot air there, though.)