I've played in and run a ton of Living Forgotten Realms games. It's true that there's no official Wizards of the Coast support for it any more, but that hasn't bothered our store in the slightest. The community support is just fine.
As you said, there are TONS of existing LFR adventures that you can download completely for free. I do strongly recommend updating older adventures to use post-Monster Manual 3 damage expressions for the monsters (otherwise, they're uniformly cakewalks unless the PCs do something really dumb).
Not every adventure is a gem, but a good DM can make any of them fun. And hey, they're free! If you read through one and don't like it, pick a different one instead.
I'm sure Pathfinder Society modules are awesome, too, but I'm only playing in my first Pathfinder campaign at the moment and it's not PFS, so I can't speak intelligently about it yet.
If you're trying to do something to help a friend and the friend is already having good sales success with LFR and you prefer the ease of running 4e anyway, LFR is probably going to be better for you. But as others said, if there's already someone in your area who can help coordinate PFS events, by all means reach out to them! The best option is to offer both PFS and LFR, of course. My local store does, and it sounds like it's working well for them.
