2ndgen. Now you have me confused, are you 15.8 or what your photo shows?

I had an idea a litlle while ago. I think it looks nice
The one with the red tape is the original.
I`ve done it all black of course. Sadlle would be SSM Regal-e, campy 11-sp group. trek bat cages.

-17 stems look so bad ass on level top tube frames

+1. The key is "on a level top tube frame". That's the look I went for on mine originally but there's a couple of things that didn't quite cut it aesthetically. 1) On larger size frames where the head tube angle is usually a little steeper than 73 degrees, the eye will still detect a downward slope on the stem. I didn't like that. Of course, fit should never be compromised for looks in my opinion, but if you can get both then why not. A good example of what I don't like is a -17 stem on a frame with a heavily sloping top tube... Fuuugly. 2) The second thing is that with today's stems (versus the quills of old), that angle at the headset cap is kinda funny looking.
If the frame is sloping, I prefer the look of a less than -17 degree stem (-6 to -10 degrees) looks good. With most Cannondales, almost any stem can be made to look badass in my opinion. I've always liked their geometries.

Thanks.

I wonder does an all aluminum frame like caad ride....
Is it too stiff? I mean stiff that it is not comfortable?

I cannot detect the difference between the Fondriest Don Race full aluminum frame and full carbon fork and the Colnago C40 full carbon frame and fork with both frames delivering a great ride. They both have similar wheels, proton and nucleon, both have Thompson masterpiece seat posts, both have aluminum 3TTT Prima 199 bars, both have Flite TT saddles and Time RSX Ti pedals.

So the answer would be no in my opinion if the bikes are set up similarly. There are a lot more variables than just the frame that makes up the ride experience. There one other thing that factors into stiffness and that is rider fitness. This is key in accessing ones own opinion of what is stiff and what is not. The numbers won't mean a thing to a rider since instruments are a lot more sensitive that the rider.