I haven't opened a masters box since Eternal Masters. I opened two of them after hording them for around 9 months. Its wasnt worth it in terms of value but it was a lot of fun. Getting a foil every pack is cool too.

I dont think I would buy any new masters set as they are producing far to many of them now. Drafting them I would be thinking more of the value than of the card that would win me the game, so I would definately not be up for that.

In terms of value, look at what foils you have pulled, and not just the rares. I remember pulling a foil Pyroclasm I think, which has got some value.