Clive
I have one of these machines and have sharpened both end mills and slot drills sharpening the flutes is not easy as it is difficult to get a smooth action as you grind them I keep trying various modifications getting better but not there yet.
I also bought the drill sharpening attachment its not very well made and does not appear to be capable of the precision required to sharpen a drill. Having said that that I cannot make sense of the instructions, so at the moment I have admitted defeat with drill sharpening. I tend to use a lot of small drills up to 6mm when they are blunt I replace them.
It has been used for the final grinding of D bits and other cutters.
Would I buy one with hindsight yes but it does not see much use about once every couple of months and I have a session sharpening milling cutters.
Olly