Longsword finesse is pretty stinky, unless you are an eladrin rogue|wizard hybrid, putting every feat you've got into that longsword.
And there is also half-orc rogues, who pretty much lose out on a nice racial feature if they use a d4 instead of a d8 weapon.
This is obviously not true in absurbum eg +20 damage is >> +1 to hit. For a rapier (or Double sword abomination) rogue you can get +4 damage with a 2w power for -1 to hit, ie a lot of your attacks by 7th level. Even +2 for 1w powers does more damage in normal circumstances. Once you are using a d4 weapon the extra w look very unappealing so you tend to choose powers with other effects, which exacerbates the difference from a damage focused rapier user.
(My dagger rogue does noticeably less damage than my mate's rapier rogue but I apply lots of status effects).
And there is also half-orc rogues, who pretty much lose out on a nice racial feature if they use a d4 instead of a d8 weapon.