I can confirm the 7610 made a very noticeable difference for my Duma vs the 7620, SB 6141, 6183.
Good job MoD BoX, your a very valuable source of information to these forums!
I've had this router for 5 days and it's the 1st minor little quirk I noticed! Good eye OP. It's not a big deal at all IMO since the features on the router are very, very nice.