Did you mean M48? The M48’s is all I use these days.. not fully as hard as carbalt but way less brittle. They do get dull but I prefer a quick sharpening touch up rather than a lot of mess in case a carbalt tip breaks.
EH - That's good to know about the M48s. I've been using Steve's carbalt gravers since he brought them out. Very reliable but they do seem a little brittle on occasion. I'm going to need a few more gravers so I guess I'll try out a pack of the M48s.