[ickledevil]

As far as im aware you definately could upgrade the fins with C4 carbon blades and some others too. (a friend has a pair) A lot of C4's new carbon blades are coming with their new foot pocket now (which is fabulous) but im sure they will continue offering, you can also buy just blades from Omer so could upgrade that way. Black fins wise.. well the obvious suggestion is carbon, C4's or omer rekord, but these come at a price and are not always suited for new divers. The Omer millenium runner fins are a solid black version of the millenium ice and are exactly the same design. One step down the performance level is the Millenium winter again by Omer. Cant comment on other makes as I seem to have become an Omer convert and use their gear exclusively.
One comment on Millenium Ice, if you get them get them new, the old series (maybe two series ago now) were not good and suffered all sorts of issues. These have all been ironed out and they come with a generous warranty. Which incidently they do honor without problem. A dive buddie broke one of his fins millenium ice recently and it was replaced rapidly and easily by Omer.