Personally I love this type of frame (though I may be biased
). It looks very similar to my team's frame.
http://www.chiefdelphi.com/media/photos/36277
I don't know if you said it already, what is the wall thickness on the tube you are using. My team always uses 1/16" wall thickness and never has any problems with strength, I will however just say that we do have a professional welder do our frame so that may help. but besides I like it, and if you are using 1/16" thickness it should be incredibly light.