Buck, and many other manufacturers, use these 'lower end' steels not because they make exceptional knives, but because they can be blanked out on a press, ground, heat treated, and finished at an economical price.
The key word here is 'EXCEPTIONAL'--that is what the custom knife is supposed to be---exceptional.
Many of Bucks higher end knives (that cost significantly more) are made of the better steels such as BG42 and S30V. It's the old 'you get what you pay for' thing at work here. 420HC simply will not perform upto the levels of the better steels.
Many of Buck's folders can be sent back to them for blade replacements with BG42 and perhaps S30V (at least this was the case a couple of years ago) at a very reasonable cost.
Personally I am not at all impressed with the Buck knives I have that are made with 420HC.
JMHO.
-Mike-