Give it a try.... But know that, in this community, everything anyone has ever tried once and succeeded at, whether that thing had any influence on the outcome whatever, is what they hold as gospel and will defend to the last shard of bottle. I've read about it, I had some astringency problems earlier this year from the sparge water being too warm but if you stop at 170°, you shouldn't have any problem with tannins. The reason for the warmth: The sugars dissolve better at higher temps than at lower temps, particularly the long-chain sugars and caramels. Short story long, I don't see any problems with cold steeping but I really don't see any upside either. Best thing to do would be test: Split the boil, cold-steep half the steeping grains, conventionally steep the others, ferment with the same pitch of the same yeast at the same temps and see if there's a difference. Get someone to set up a blind taste test and see if you can get it right more times than random chance would suggest. And let us know how it comes out.