competing interests...
just a thought... for mixing, you're going to want pretty neutral monitors (which the 624's will do) you may be unhappy with the utter lack of bass, and need to get a sub for them... don't know about the genelecs first hand...
For mastering though, what you want is something much more akin to audiophile type speakers, with full range response (think those sexy tower monitors in crutchfield all the time) since what you do here will be what the faithful consumer ends up hearing.
hope this helps.
Good luck on your quest
rich