I probably haven't watched as many fights as you. However, I have been watching boxing for about 20 years now.
I will go on the record and say this. Mayweather is the best defensive boxer I have ever seen. You are right..the mofo is not hittable. And even when it may appear he is getting hit, is not really a clean hit..he is rolling those punches off. If he had a heavier hand, I think many boxers wouldn't step into the ring with him. He definitely isn't a "puncher" but he definitely doesn't need to be.. because he can just avoid the shots and "outbox" you.
That being said..I want to see him fight a fast boxer who can hit.
I am NOT comparing him to Roy Jones because although the comparison can be made because of their freakish speed... Jones was not a great technical boxer and they are in different worlds defensively..no comparison.. But because he is so fast and has the roll perfected..he never gets hit... I want to see if he has a CHIN...and I think Mosley is fast enough to hit him...and I would have never expected for Jones to have such a glass jaw...so I want to see if Floyd can take some shots....but shit might not happen if no one can hit this muthafucka