I think you are missing my point - M3 is PERFECTLY doable with a good skew, you DO NOT HAVE TO buy pretty expensive carbide tools with a lot of inserts. With a skew I make M3 pen faster than wooden. I do not say that carbide is worse (may be better) - but it isn't a necessity.
Trustone, for example - is really hard to do with a steel, carbide is much better for those.
And I'm writing this to those, that DO NOT HAVE CARBIDE TOOLS, but are willing to try M3.
Buying new inserts... is like a buying new drill bits every time they get dull. It depends on quantity and light/heavy usage. Carbide tools and inserts are common in metalworking industry for a long time now, that type that we use as woodworkers - too. I can make a handle for those inserts in, say, 1hr - and I prefer that way. Cause I will learn something new from that.
I make purchases from US retailers once in 2-3 month, big orders. If in the middle I will run out of inserts - it would be disaster with International shipping rates and delivery time. I'm thinking about purchasing those tools for Trustone, but still I'm thinking, buying a tool or just a pack of inserts, or buying metal-working inserts locally and making a holder for it (as I can buy new just every day). It's like buying a handle for a woodturning chisel - why, if I can make one better suited for my needs?
PS As for a skew - I have several modern (no-brands), but all of them sucks in comparison with this Marvell tool. They are just different in all ways.
PS2 take a 20x loop and look closely on your cutting edges on all your tools after some usage, especially carbide after trustone - you will see something new, possibly
PS3 let's close discussion on carbide tools, ok?