Next month I'll have my K30 a year, I've never had a problem shooting vertical, when I see grips online I think: horizontal to vertical & back, I'd change my hold twice; have to remove it to get to the body battery or store it in my bag; have another button to power on & off; Don't have camera/lens balance issues, my lenses are light; reason for owning a grip (speaking for myself) is the cool factor.
Still yes, I want one but, don't need one.
A student myself, alone in Los Angeles, it feels third world sometimes but, I love photography & I love Pentax. I've spent way more than I have. Still I can't complain. Being a photo major, I feel it's an investment.
As for Pentax quality & features: at my current skill level (and a few levels higher), I know my gear could easily out perform me!
In fact, the only issues I've had with my gear(PRAISE GOD!!!), are only user errors which, I usually solve myself.