What is your opinion on vertical grips?

I've got the vertical grips on my A77, A99, and even my Maxxum 7D.  The added function and ergonomics when shooting portrait orientation just can't be stated enough.  Even providing an extra handhold for the left hand while shooting in landscape with a short lens as someone mentioned earlier in the thread is nicer.  Add to all that the extra stability and balance gained, along with the extended operating time before pulling batteries, and it quickly becomes something I will never want to give up.  If there were a grip with just extra battery slots for my X-Pro1, I'd get one in a heartbeat.

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Sony A77, A99, Fujifilm X-Pro1, KM Maxxum 7D