I use hand held meters, either Gossen Luna Pro or Weston IV or V. For me, the trick is having a good pocket or camera bag so that the meter is easily stowed and retrieved. I haven't tried the camera mounted units.
I like the Gossen because it is easy to switch between reflective and incident, and the null metering readout is great for rapidly changing light.
The Westons (IV and V) are great, especially in bright light, because you can watch the needle and adjust the dial as you pan the meter in reflective mode; and in reflective mode, the meter is small. I take the meter out of its case, as it easier to use, with less fiddling to swing the case flaps open and shut. The incident mode works well, too, but it takes a little juggling to switch between modes with the separate invercone diffuser. In low light it can be a bit of a fiddle to flip open the light hatch to switch to sensitive, low light mode.
Mostly this is a good system, but at times the separate meter does seem like one too many things to handle.