Quick update. If you keep up with the Miiverse community for Smash Bros, Sakurai has his own area to post pictures and updates on a regular (daily, I believe) schedule.
Things posted there that I haven't seen on this post yet that are relevant:
Marth's slices have been shaded to highlight the tip to make tippers much easier to see. You can see this in some of the screenshots posted already. Supposedly, that highly shaded area IS the tip. So we can guess about range accordingly.
Sakurai also made a post regarding Shield Breaker. There wasn't too much explanation behind it, but he said something to the effect of the Shield Breaker getting a buff in SSB4 to make it more useful in combat since "not many people use it". The only thing going with the post is Marth with a dazed Megaman with the caption explaining it was just after a SB.
But yeah. Pull out your 3DS's and WiiU's. That blog is our best source of up-to-the-day info right now.
EDIT: Here is a link to the page I was talking about.
https://miiverse.nintendo.net/titles/14866558073037299863/14866558073037300685