I agree with a lot you say, but...
Floyd might be one of the bigger risers of late. A lot of "experts" have him rated equal to Blackmon. And I really disagree with your thought that he might not see enough targets if he were to be drafted. David Nelson had no problem finding a niche, and I would expect a supreme talent like Floyd to have a large impact from day 1.
As for Keuchly, he's really nothing like Matthews. Totally diff. positional types and athletes.
Anyhow, both are good players. I just see Floyd as a pro-bowl type talent. I've said all along he reminds me a lot of Moulds. He put up numbers with some pretty lousy QB play at ND. He seems to do everything well. I wouldn't be surprised if he had 60+ rec his rookie year.