Axxis Metalmasters are usually around $40-50 a set (i.e. $40 for front set, $40 for rear).
I personally can't see any reason for sticking with the OEM brake pads, and I am a *huge* proponent of OEM parts. (other than brake pads, I can't think of many non-OEM parts that I use).
I've used Metalmasters on the road and on the track for a total of over hundreds of thousands of miles, and have never had any problem whatsoever with them.
On my new C, to keep the wheels looking decent, I have to clean them every 2 days. I don't have the time for that, and think it is ridiculous. But, mainly, its just completely unnecessary. I also don't like all that corrosive brake dust building up behind the wheels, on the calipers, suspension, etc. They just make a huge mess.
The day they become available for the new C, I will get them!
As far as how long they last, they are very long lasting. I put 60,000 miles on the fronts on my Porsche 914. They will last longer than the OE pads.