Falco's even with Fox, I think
The matchup seems even cause Falco's laser halts Fox's approach, but as with any other matchup, Falco has great stage control and then he gets gimped and the match is even. I know a lot of people feel like they'd rather go Falco in the matchup, but to be honest, in high level play the matchup is just really even cause Fox has so many good options against Falco.
To be honest, I think the matchup is completely even but it differs depending on the stage that's being played. In terms of neutrals, Fox is going to have a slight lead on FD and YS, but Falco is going to have a slight lead on BF, FoD and DL. Pokemon Stadium is kinda iffy, I know that it's one of Fox's best stages but Falco does really well on it because there isn't a third platform for Fox to avoid his lasers and it's really long and wide so his lasers do well, yet there's some platforms to allow him to escape the cg and upthrow > upair.
If you ask Mango or Jman or Shiz, they will tell you the same thing about the matchup, it's even. If not, it's defs 55-45 for Falco. (edit: and I guessa Zhu agrees with the matchup being even?)
P.S. I think somebody brought this up so I'll bring it back up...Falco vs Marth and Fox vs Marth is even when you have full knowledge and experience in the matchup. Otherwise, some problems can arise that can lead people into believing there's an advantage for one of the chars. For example, if you have little experience vs Falco, your Marth may not be able to get grabs in and you may not know that sweetspotting the ledge is necessarily, or you get owned by lasers too much, etc. To be honest, I could see the matchup being about 55-45 for Marth vs Falco due to stages but that's about it, I wouldn't say 60-40, especially for Fox vs Marth.
P.P.S. Zhu, you live in Irvine? I was just there yesterday, I'm on vacation, we should've smashed! </3