Weight is secondary, aesthetics and ergonomics really takes the cake for me.
Also, why are you mentioning a Ritchey stem? How do you suggest that in a thread for "fancy aero levers"? Anyway, compared to a Thomson or my ITM stem, I just don't like how the bar flexes under sprinting forces with the WCS series. I avoided the Syntace stems for the same reason, despite their nice weight.
Forgive me, I'll try and think twice before making suggestions.