Well if you are buying a 9mm then they are all German made so I don't see were importer makes any difference. Earl may disagree but I don't buy his story line....I have one Interarms and two S&W's and honestly the importer doesn't make a difference except for the import markings...sell what you want, keep what you like. But my first advice is NEVER SELL A WALTHER. If you do you will be sorry.
If your Interarms pistol is one of the first 6000 imported, I'd be interested in buying it (though I don't have the cash right now, just bought a 642).
The first 6000 or so P99s had a slightly different AS trigger that just happens to be what I rented to make me love the P99. Eventually I'm gonna track one of those down just to compare the triggers side by side.
As a member mentioned in a previous reply, you will ultimately be sorry if you sell any of the Walther's. If though, you did had to sell one, possibly the newer frame version would be the one to part with, as you could always pick another one up down the road. The early Interarms imported pistols are nice to have; the models with the split trigger. I have one that is in the low 8K serial number range. I am quite partial to it...never has given me any problems.