Not sure why Superman (post-crisis, righ?) still being rated that slow, one time he suggested to have femtosecond reaction, and that without counting some statements fro the authors.
You mean this?
http://static.comicvine.com/uploads/original/11113/111130781/3636108-3150638629-super.jpg
Superman never actually claimed/stated to had femtosecond of reaction time or combat speed.
even Batman mentioned about Superman having zeptosecond reaction (still without source, this was said by a Nerdist scientist).
I heard this too, but i haven't found anything about that, so i must guess that it just some made up crap for some wanker.
Anyway for the main topic, while i do still think that combat speed and travel speed are not the same thing, i do think Superman could still reach MFTL+ speed in combat, but only when he can accelerate.
While regardless his best instant speed feats are just around MFTL, if he keep to accelerate for enough time, he could reach MFTL++ speed even in combat (this is how he can still more or less keep up with speedforce users).
But he need to accelerate for reach those speed (aka he need time to build that level of speed, he cannot instantly became MFTL+), so when he stop his momentum he would return to had only MFTL speed.
So characters that are normally MFTL+ speed without acceleration, would still be advantaged in raw speed.