Best thing to do if you are going to tool steel is slow your speed down. Both the travel of the tool and the speed of the arm rotation. I personally would change the angles when going to tool steel and i've been thinking about doing it for a while as my diamond bit could do with lapping. As an example for proving that slower is better when cutting your comm's - The diamond bit I use is 9 years old, it was resharpened once because I did something stupid. I use a mabuchi motor in my lathe and power it with a 4 cell pack. I must of cut thousands of comms with that thing and it still cuts more that adequately. Increase the rake and clearance angles by about 5% as compared to Diamond or carbide, polish a very small radius on the end of the tool with a very fine grit stone. You should (in theory) get a way better finish with this than carbide bits, maybe better than diamond too. It's heat/fridtion that wears the tool, keep them low at it should last a good long while.
One last thing, keep the distance that the tool protrudes from the holder to an absolute minimum, this reduces vibration which cutting tools don't like.
I was a machinist for 6 years, I cut a lot of nasty stuff, 99% of the time it's the speed of the material under the cutting edge that causes the tool to dull.