Very interesting and informative. Thanks.
I have recently started using Aldo's 52100 myself and chose to heat treat the way Ed Fowler does--sort of (modified for an annealed foundry steel).
Ed does massive reduction forging on his steels and does three annealing cycles (he does many things in threes come to think of it).
I do not anneal. I do not quench 3 times (tried it once), and I do not put my blades in the home freezer as he does since every bit of advice gleaned from this network in the 13 years I've been here indicates that this has little or no scientific merit (not to discount Ed's considerable success in high performance blades-just a choice on my part).
Ed uses Texaco type A quenchant. I use peanut oil at *130
He uses a gas forge, magnet, and color to determine critical temp. He also does what he calls a 'flash normalizing' three times. These are the processes I borrowed from his published instructions. I've had good results.
It is entirely possible that I'm just 'Forrest Gumping' my way through this.
http://www.knivesby.com/Ed-Fowlers-heat-treat.html