After playing some 50 odd games as Marth, comparing to old videos, replays, and keeping up with the Smashboards and Reddit threads I am concluding Marth is unchanged.
Marth's unstaled F-smash could always kill barely upwards of 100%. F-throw to f-air has been a combo all along as well as d-throw to Dolphin Slash working until around 150%.
While it's really cool that we've discovered some new stuff with Marth, I unfortunately believe very strongly that all of it existed pre-patch.
Anything that 'feels' different from before has just been that: a feeling.
On the plus side, the potential that there were changes to Marth inspired us to dig deeper than ever before into our character. simply being told that there may have been an altercation to Marth's d-throw inspired me to look at his other throws and I discovered that f-throw had true combo follow-ups in training mode. Even though I'm certain that the combo was always there, I wouldn't have though to try looking at Marth's grabs for follow-ups and it would have gone undiscovered until much later.
Smash 4 Marth is obviously Marth's weakest incarnation, but it's not bad and has been brushed aside far too easily. As much as we would like buffs to the definitive Smash Sword Guy, he still has what it takes to carry a player a mile or two. Besides, there's always next patch anyways.