I am in a similar situation. I have had Shadow Dragon for a little while, but just recently started playing it. I am amazed with how different our runs are!
I regret losing Frey in the prologue, as I haven't used Gordin at all. I use Ogma and Navarre religiously. My Marth not very good right now. I lost Barst early on, so now i have been using Darros and Bord (for his c axe skill). There are just so many units in this game that runs can be so different.
I am on Chapter 7 right now, I think.