I know lots of folks like filework on the spine between the handle scales but personally I've never liked it much and have never done it.
so now you have to decide epoxy or no epoxy Bruce, with no epoxy something kind of looks like its missing but with epoxy....and this is just my opinion, years down the road that epoxy filled filework isn't going to look like it would next month. and that's my reason for not really liking epoxy filled filework. I've seen knives with it 5-10-20 years old and one of the first things that stands out to me on those knives is shrinkage or what ever happened to the epoxy, on the other hand just about every knife I make gets filework, just ahead of the handle going down the blade.
But where your standing now I would probably do the epoxy because like Sean said, if you don't dirt and other stuff will make it's way in there
leading to someone down the road picking at the stuff and possibly damaging the liners you used there...which will lead that person to say...why didn't the dumb azz that made this knife use epoxy in this filework?