Hi Peter
I was so close to buying one of those, but in the end balked at the expense. Once you get to know your scope's temp/focus characteristics you can do a pretty good job setting filter or time delays in SGP rather than temp adjustments anyway.
In the end I bought one of the cheap temperHum devices off ebay, very aware it wouldn't work with latest SGP, but "just to see".
http://www.ebay.com.au/itm/TEMPerHUM-PC-Notebook-USB-Sensor-Thermometer-Temperature-Data-Logger-Recorder-/152318823468?hash=item2376e8cc2c
Very pleased with it to be honest. Have it plugged into the USB hub on my scope. Does a great job of graphing and showing in realtime temp and humidity through out the evening, along with dewpoint. Values seem pretty close to local weather reports and my old thermometer. Have heard they can be variable between devices (like chinese EQ mounts
)