Decoction For Mash out Question(s)...

ok so today i plan on doing a single step infusion mash with 14 qt h20 and 11.75 lbs grain (1.2 qt/lbs)
Usually for the mash out i add enough boiling water to raise the temp to 170. But for this batch i want to try using a decoction instead. Im basing my technique on an article i found on this site.

So after 60 min @ 150F im going to remove 4.5 lbs of grain and enough wort to create an oatmeal like thickness. (40 percent would be 4.7 lbs, which is supposed to raise the temp by 28 degrees, im using 4.5 because its easier to measure and i dont need 28 dgrees, just 20) Im adding this to a cold kettle and slowly bringing it to a boil, stirring constantly. I boil for ten minutes then return to mash tun. If the decoction gets too dry i add some more liquid wort.

My questions are these:
1) Is this a sound technique?
2) should i weigh the decoction, or just eye-ball it using 1 qt= 1 lbs of grain estimate?

I may be wrong here, but I would tend to decoct the thin runnings for the mash out. I reckon if you decoct the thick mash for a mash-out step you could end up releasing starches that will not be converted because the enzymes have been denatured. It may be better to do a beta to alpha decoction instead.

I concur with mysterio...to decoct for mash out just run off some wort (don't worry about recirculating) and boil it, then return it. You definitely want some type of enzymatic rest following a thick decoction due to the starchies you'll explode open.