I've never been enthusiastic about OEM nav systems. They're nicely integrated into the dash, but their user interface is rarely the best and they're almost obsolescent from day one.
But installing an aftermarket and portable nav system has its issues. The installation can be kludgy and create problems. I wanted the cleanest install with the least impact on my vehicle. There were four possible candidates: 1) OEM Portable navigation (nicely hidden wires, but a hole in the dash); 2) Kuda base and ball mount 3) Proclip (3 different installation locations) 4) Pro-Fit Mount.
It got down to the Kuda and Pro-Fit, and the Pro-Fit was quite a bit less expensive. The mount is an angle bracket that projects a mounting ball about an inch above the dash wood trim. Remove the trim, start two holes and screw the bracket (carefully) to the underlying dash. While the trim was off, I routed the power cord underneath, out the passenger side, down underneath the cloth trim at the door edge and under the lower dash panel. To make the bracket less intrusive, I painted it a gloss black.
I elected to retain the power plug vice hard-wiring the power cord (I've had several bad results with spliced power leads), so it intrudes slightly (E92 LCI) into the passenger footwell ... it would have been neater with the old style flashlight power plug in the glove box.
One small issue, the bracket does allow the garmin to vibrate slightly (only slightly) over rough roads. I attached a small felt pad behind the mount to brace it.
Trickiest part was getting the cable behind the cloth trim without damage. Works great, and I can uninstall at resale time in about 5 minutes.