
The Brewpi definitely has a few issues with (slight) overshoot when making step temp changes - e.g. the beginning of the brew, when my wort was at 19 and I was targeting 18.5 - but once it settles it is amazing, and (barring my messing about with the profile and inducing another step change mid brew) the temp of the beer has never been more than 0.1C off the target. Whether or not I have set the best target/profile is another matter, but with logs you can see exactly what you did and recreate that/experiment as required. Plus there is a lot of interesting info to be gleaned from the temp differentials as well - e.g. it is clear to see when the yeast start going exothermic when the set temp starts becoming much lower than the beer temp - as much as 3C at peak. It does make me wonder what temps I have really been fermenting my beer at in the past.. So safe to say I'm sold on this, and quite happy - plus a nice thing to keep track of from the office

graph with just set/beer temps:
