I don't typically use my hydro for my runnings, but I sure refractometer the runnings to death!! So far, I have good faith in the refractometer during the mash/boil/OG - I've tested the results against my hydrometer and come within +-.001 SG. I still need further testing on my FG readings to make sure the refractometer conversion algorithm properly compensates for the presence of alcohol.
Also, I typically mash at a consistent 154F, but this time I was going for an DIPA, hence the mild step up attempt. I wanted to get a more fermentable wort to help mitigate the high sweetness caused by a higher FG due to mash temp.