If it is a valuable domain it is an investment, beyond your intent to eventually develop. So from that point of view it will gain value if the market for domains grows (and lose value if it drops). So from an invesment perspective it is a question of what would you do with the money if you sell? If you do not have a good use for the money now, either a better investment or it is needed for debts or a special purpose, then consider holding as an investment.
Domains are not very easy to sell quickly for top dollar. A quick sale usually means sale to an investor (reseller prices). If you hold for a few years you might find that end-user.
And Yes, Matt Hasselbeck Rules --- Go Seahawks!