Well I have a bit of an issue with the whole thing, since I like propably a lot of other people have horrible experiences with clients made by curse. Most people who used their client for WoW know that it was terrible. And a bunch of people made something similar, which was more secure and with better functionality and got the downloads from curse page... and was shot down quite quickly by curse.
That's the reason why I can't really believe that they allow anybody (iE 3rd party launchers) to use their service. They might officially allow it, but place so many rocks in their path that it isn't worthwhile. And their launcher... they have to create something better than they ever did to even be as good as the current FTB-launcher. Everything they created until now was more or less a total mess, exspecially under security points.
In the end my expectations aren't that high, which also means it is a lot harder to be dissapointed. However the thing is, FTB never was about money. This Forum is incredible Ad-free and nice to read. The MCF is terrible in comparison and I don't bother reading it and if it is surely adblocked, because it is terrible annoying and one of the few places I use adblock.
But since slow already mentioned that they didn't sell anything to curse I actually expect them to do whatever they can to step back from this partnership. My biggest fear isn't that the new launcher and what curse has in mind sucks, my biggest fear is that if it does nobody cares and I have to use Tekkit or propably other launchers.
So if their new launcher is good and only has some hopefully preselected adds (which would make security much better... and honestly being at the client should pay far more than being at the side, because no adblock) I wouldn't bother. That it might download a bit slowly can be problematic, but on the other hand there are only a few large mods and my folder with mods for magic farm is 80mb and for monster it is 120mb... that's not that much even if the download-speed without premium isn't great.
So I'm not enthusiastic about it because honestly I doubt that a lot will change if they do it right. However I doubt that their general client (and I think they still want to keep it universal) can compete with any minecraft-specific client.