I bought a Sekonic L758 6 weeks ago to use with my D800, after watching the Joe Brady (Sekonic) videos on YouTube.
It has been a revolution for my photos. I shoot almost exclusively manual and prior to the meter i was frustrated by the number of bad exposures i was getting.
I use the meter everywhere, even when i took my kids to the zoo recently ...
The meter provides both a incident meter and 1 degree spot meter that i have found very accurate (without needing to spend the additional 300 bucks to buy the calibration image that lets you further refine the settings to your cameras lens/body dynamic range).
Shots in even (even midday) light are very easy to determine for a great result. And shots with light and shade or reflective surfaces are made much easier having the ability to both take incident and reflective readings.
Since using the meter the number of clipped shots has dropped dramatically and i am able to concentrate more on focus and composition .... so i am very happy with the investment.