I have yet to replace the knock-off MB-D11 I purchased two years ago, but my thinking is this: If I can buy a new one for $50, I'll have to buy 5 knock-offs over the life of my D7000 for me to think about buying the genuine MB-D11. And right now, it doesn't look like that's gonna happen.
I also bought a knock-off MB-D14 for my D600, and so far it's served me well.
My best advice about grips is this: If you actuate shutters for a living, buy Nikons. If you're a casual shooter (like I am), buy the knock-off. If you're concerned about the knock-offs breaking, just buy two and have a back-up on hand.... you'll still be money ahead.
I hate when people ask me what I see myself doing in 5 years...... I don't have 2020 vision!