I would have been interested in Merriman 2 years ago, but not now. He hasn't done anything in the league for 5 seasons now. In the past 5 years (2008-12), he has played in 33 games, started 22 games, recorded 6 sacks, and 70 tackles.
In his past 32 games, Kroy Biermann has started 4 games, recorded 6.5 sacks, and 82 tackles. At best, you're signing another Biermann. But again, remember, it took Merriman 5 years to do what Kroy did in 2.
If the Falcons were seeking more help at DE, then Mark Anderson would be a much smarter signing. But even he would probably fall flat on his face (he's only had 2 good years in his 7-year career).
If the Falcons are going to try and upgrade their DL, I think they should be looking at players like Trent Cole or Brandon Graham in a mid-season trade with the Eagles. They have a bit more left in the tank than any player the Falcons could pick up off the street.
I don't think Seymour cares about Merriman either. He was clear earlier this month, that he has a price that he wants the team to meet. And he said if they don't meet it, he's willing to retire. Clearly players like John Abraham weren't willing to go that far, although he got a decent deal from Arizona (2 yrs./$6M, don't know the guarantees). Frankly, IMO Seymour isn't worth more than $2.5M/yr. If his price is higher than that, then the Falcosn should just move on and hope some good young DT gets cut at the end of the month.
"Vincere scis, Hannibal, victoria uti nescis" -- Maharbal, 216 B.C.E.