I use the Metz 58AF and they will do everything the Nikon flash will do, and are easy to use even with TTL metering. The USB update feature is not so important with Nikon, with Canon it's a real plus as it gets around the built in redundancy of Canon. There are already 4 updates for Canon on the Metz website, none for Nikon.
They work well with multiple flashguns and can be used as a high power Master.
The have some neat features, such as there are 3 sensors for picking up the control flashes, so even if you fit a soft box which would obscure the Nikon one they still work.
Chris