I have the Woodcut Bowlsaver, 3 knifed version, so far it has been excellent over the last (almost) 6 years.
I too would suggest making fewer cores with more than enough material to allow individual shaping of the final product. I once did 5 cores and 5 bowls from a single blank, never since. I just did it, coz I could.
In general, I get 3 very good sized core blanks from each blank of timber; quality over quantity comes to mind.
As for replacing the tip, I'm not the biggest user but when I get a felled tree, coring 10 blanks by 3 = 30 coring runs, is not uncommon. My Stellite tips still look pretty new, but they all get a swipe or two after each coring with the credit card sized "very fine file" from Woodcut, when I bought the bowlsaver.