Haven't read through the entire thread however I thought I should tell people about my experience in case it can help anyone
I used crosby and bakers yeast energizer since my LHBS didn't have pure DAP. I talked to one of the guys and he said that it was about 90% DAP when he looked it up so I figured I would shoot for just a little higher. I also read in here that the Malliard reaction didn't start until after 240ish. So my recipe is as follows:
4 lbs sugar (full bag, regular white beet sugar)
2 cups water
heat to 230, add 2 tsp yeast nutrient.
(it took a long time to come above 230-260 on a gas stove with a smallish flame)
It was taking forever to get up to 290 where I planned to stop it, I went away from the stove for about 5 min and it shot up to 320. I said 'ohh crap' and put two cups water in it.
At this point it was a amber color and had no burnt (or toasty) taste to it, but did have a very 'toasty' smell. I checked the temp and apparently my candy thermometer was about 10-20 degrees higher then it should be, so it probably only got up to 300ish. I added about 2 cups very slowly after I turned off the burner. When it got down to about 240 I added 1/2 tsp of the nutrient and heated it up to 280. It took forever to get past 260 then moved pretty quickly. It darkened a LOT on the second warm up, and developed a LOT more complexity. after it hit 280 I added another 1.5 cups water and turned off the heat.
All said and done it tastes a lot like the D2 Candi syrup I bought for my last beer. I didn't have them right next to each other however my syrup seemed to have more layers of flavor and stronger/sweeter overall taste. The first time I tasted the Candi syrup I bought it was kind of underwhelming with the flavor, tasted weak. Definitely not with what I made, and they were both very similar in viscosity.
I would highly recommend trying this. I will put it in my 3$/gal Belgian beer I am trying to develop. It is 10 lbs pils malt and probably 1/2 this syrup so I can tell what it tasted like fermented. I will be putting the other half in a ginger cider to add some complexity.
Ohh, I am in Iowa if anyone is trying to figure out how altitudes figure into the equation