I have just purchased a used HED Jet 90 rear wheel based upon the ultimate scientific reason - it was cheap! I have reviewed all that I can find that compares one brand (HED; Zipp; Campy; and then off-brands), and at the end of the day, they all appear to be equal-ish.
I am in the market for a front wheel. Ignoring the issue of mixing brands for the moment, does anyone have any thoughts on a tri-spoke vs. a medium depth rim for the front?