In addition to my role as color commentary contributor to this thread, I log thermometry data to confirm Dave's recommended brew temperature management techniques that he's developed using more holistic methods (namely "water dancing" and taste testing). This tag team approach speeds the review process and helps assure consistency across the
Buyer's Guide series.
Below are a couple videos showing my early investigation using Eric's
E61 thermometer adaptor (a production version of Dave's
do it yourself model). The first video is the traditional flush and rebound, as described in
HX Love. The target temperature is around 200F, which worked well for
Rocket Reserve:
[gvideo]http://video.google.com/videoplay?docid=6270636544465718678[/gvideo]
I've noted some HX espresso machines perform poorly with the "flush and go" technique, others will only perform well with flush and go, and some work either way if you twiddle the boiler pressure. My theory is that most of this preferred usage is attributable to the heat exchanger size and injector depth. The Vibiemme exhibits a classic E61 "HX hump" and seems to favor the traditional flush and [short] rebound approach.
After a few tries, I wondered if the Vibiemme would produce a flatter brew temperature profile using Eric's "flush and wait" approach. This alternative to flush and go / flush and rebound hasn't been talked about much in the forums, but in a nutshell, it's a slow reverse surf. I flushed down to ~198 and then watched the grouphead thermometer slowly rise to the target temperature:
[gvideo]http://video.google.com/videoplay?docid=-2074075821549000604[/gvideo]
I overshot the target temperature, but the overall profile is much flatter. It's a slow technique and only practical if you have Eric's adapter, still it may be worth updating the
HX Love article to describe these three techniques (flush and go, flush and rebound, flush and wait).
Those who've watched
flush videos with the thermocouple may notice the thermometer reacts more slowly compared to a type T thermocouple. It catches up by the last 5 or 10 seconds and the readings merge, similar to the curves shown in the thermofilter versus thermocouple adapter graph:
With the flush and wait approach, the readings track much more closely, maybe lagging by two degrees and catching up before the midpoint (sorry, when I made the video, I wasn't looking closely at the thermometer after I raised the lever). The ever industrious Eric has a type T thermocouple that's the same diameter for those who wish to swap between ultra-fast thermocouple responsiveness and the more aesthetically pleasing all-in-one thermometer / adapter. While I can readily nail the brew temperature within one degree with Valentina nowadays using a thermocouple, I think more Zen would be required for that level of consistency using the thermometer version. Then again, what would I do with my weekends without this extra challenge? Buy a double boiler and make espresso all day?
Or at least in addition for those not of the MTV generation? 
