The Aluminum frames from Principia are by far the best in the aluminum frame on the market, they would make Cannondale look like cheap junk! Principia has the highest level of stress before frame failure of any other AL frame on the market. If you want the best aluminum frame Principia is the one to buy.

Personally though I don't like aluminum frames, but that's a whole another issue that would cause a flame war you would not want to see.