That's a very good point on Matt being in the final (either with or without Dave), wish someone had asked that. Whatever his answer would be I know what most people would think his real response would have been in those circumstances. If he said that he wouldn't have mentioned it then he may have tried to excuse that by saying that he wouldn't have been around the jury house feeling guilty around those making the decision.
Although I did feel earlier on that it was too unfair them knowing each other before I do think that aspect can be overplayed anyway. They hadn't been that close outside and in the game they did go their own separate ways eventually anyway, that ironically caused the secret to come out and made it an issue. It was really up to the others to not be as influenced by Dave and later Matt as they were, and some even noticed that they were together but didn't do much about it.
Although Lisa (as the winner) inevitably got credit for taking Matt out, Dave strictly did it, or maybe you could even say that Matt took Matt out (he should have kept closer to Dave, he still could have beaten him at the end). At the reunion they started off saying the Brad elimination was a Lisa move too, but as they talked about it Matt was obviously the person behind it.
Lisa was preferable as the winner to Tess of course but at the same time she wasn't either as big a character or as central to the story as Matt and Dave I would argue. A story they skipped at the reunion was Dave's immunity idol and another was Lisa's plan to forget to bring Matt's idol to tribal. The appeal to Dave was a desperate last ditch move which only worked because of Matt not keeping Dave informed.
Dave really should have been better prepared at the final tribal for the question about Matt. From what I heard Matt and Dave had agreed while in the game not to mention any previous connection they had, but if one of them went to jury they would just leave it up to themselves individually as to what to do. It would make sense to even make a prize money agreement as well (though that would have to kept secret I expect). That they seemed to leave things up in the air like that suggests they aren't as close as some made them out to me.