After analyzing data from various sources for flatplate and evacuated tube collectors, I find that flatplate collectors perform better in the majority of situations. There are also considerably more cost effective. However, the SolVelox Glycol can be used with all types of evacuated tube collectors and flat plate collectors.
For more details about collector types, I recommend an exerpt from Solar Water Heating by Bob Ramlow with Benjamin Nusz.
Click here for another article which explores the performance differences between flatplate and evacuated tube collectors.