big fan of both. The Sacrament does feature a lot of the mumblecore crowd but i like those actors (Seimetz, AJ Bowen) and it's probably a big part of why i like the film (so maybe you won't so much). I like the way the escalating dread is done, it's effective. i didn't know much about it going in...again, probably a good thing. Also the song they play over the opening credits had me on board straight away!
The Invitation is ace, really liked it. don't want to say too much apart from thumbs up. quite poignant in its way