I'm looking to get another flash to supplement my SB-900. Ideally, I'd like a SB-910 Nikon but I'm not very keen on the price (AUD$637). Anyone tried Metz 58 AF-2? (http://www.metz.de/en/flash-units/product-ranges/system-flash-units/mecablitz-58-af-2-digital.html) I'm mostly wondering if it will play nicely with my SB-900 (ie, no quirks) if I use them in a group. The Metz is somewhat cheaper.