Depending on how his new deal is structured, Harvin could be a lot cheaper for potentially one year (this season he was due just $2.5M) before getting paid elite WR money, but I don't know if that one year discount is worth a 1st round pick, much less the throw-in 7th and conditional 2014 mid-round pick.
Harvin is clearly the better all-around player, but I rarely agree with teams parting with a first round pick, especially for a guy they'll have to pay a lot, too.