So here's a late review... I ended up buying BOTH the Pearl Izumi Vagabond II (2002 model I think) and the Cannondale Morphis.
The Vagabond has been great. Likely not the most breathable on the market, but comfortable and cuts the wind and looks good. I wear it for MTB and occasionally around town.
The Cannondale Morphis (2007) was a disappointment. The jacket is very breezy around the armpits and back but the arms themselves hold the sweat (like gman noted). It's nice that the sleeves (one piece which includes the upper back) can be easily removed while riding. However, most of the reflectivity is on the removed back panel and beneath that is just mesh. I found that if the temperature outside demanded a vest, having such a big mesh area defeated the purpose. I bought it for bike commuting and jogging, and pretty much only use it as a vest to improve my visibility a bit. Maybe it's more useful to serious road riders who position themselves differently?
That's all I got!