The slots I'm cutting are 1.4mm wide and 1.3mm deep. (see my Gcode thread and look at timing pulleys program if you want to know exactly what's what...)

As a cutter that small is stronger radially than axially.
I think you meant stronger axially.

I think it's center cutting, not sure ... quite a big change to the code to do that but worth it I guess.

Where do you get the 0.01mm chipload number from, experience (if so good)? It's about the average value I found from checking various websites. I've used 0.025m chipload with 2mm 3 flute endmill successfully:

http://www.youtube.com/watch?v=p13LZ6IxmgY
(wrong title on that video!)

I may just grind a form tool to do this in the end, but it'll be nice to try it.

Experience! Only 7 years...much less than yourself I guess.