Maybe I'm reading it wrong but are you saying that your XC DMT stones wear out so quickly that you have to purchase a new one with each new knife you buy?
If you reprofile from 20° per side towards 10-12° per side on a 9-10" stainless blade, with an Extra-Coarse 6" Dia-Sharp that has already sharpened one such knife by the same amount, then from the wear on that hone you are looking at 4-5 hours of hard work for a poor result, instead of just one or two hours for a great result... It's that simple, and a hard earned lesson for me...
And I do mean that: Those five hours of work will result in an uneven, assymetrical and inferior result compared to the one-two hours if you use a brand new 6" Xtra coarse...
Since I am lazy and want flawless results quickly, especially with a hard steel like S30V (RJ Martin 10.5" Blackbird) or with D-2 (like the 10" Lile "Mission" I did recently) I always buy
two extra-coarse Dia-Sharp 6" hones for each new big knife ($36 per hone: $72 in total for one knife): One hone per side(!) to bring it down from the ridiculous 80° inclusive that the pristine 30 year old pre-dot Lile came with (fortunately on a beautifully thin 0.028" edge bevel shoulder thickness)...
The two Xtra-coarse hones I used for the 10.5" RJ Martin were so worn-out from taking off 8° per side (beautiful job though) they subsequently ruined the 9" Farid 440C FB prototype I tried to sharpen later on with the same two hones...: I sent it for a full re-grind at RazorEdgeKnives, and learned my lesson well: Two new X-tra coarse for each new big knife from now on...
I have no understanding how 20° per side can be considered even remotely useable... Who cares if it shaves: This is not sharpness...: On Randalls 10° per side is virtually bulletproof, and refuses to chip almost no matter the abuse: I have to admit some Custom makers have not proved so solid with the same angle on the same 440 stainless steel, even with thicker edges... Unfortunately again, most Custom makers do a much better job of symmetry and finish than Randall's medieval-level precision (the only thing Randall does fairly well is keeping the edge centered and paralell to the spine: That's about it, very rough otherwise except for the sheath and handles)...
I did buy two new 6" Extra Coarse Dia Sharp hones for the Lile Mission in D-2, from which had to take off over 25° per side, but on a thin edge, and I am glad I did, as the result is good and that thing "ate" the two hones just about dead, one per side, with a good 3 hours...
I hate sending in knives to professionals (they often lose a small bit of length under water-cooled power grinders, which aggravates me no end as often knives are
already way under the specified length straight from the factory -especially Randalls!-: I also dislike it when there is a lot of dead space at the tip fo the sheath: Where does the endless shortening end?...).
Taking off 10 or 20° per side,
by hand, on a 10 inch stainless blade is a grim job...: $70 of hones on a $1500 knife is a bargain to make life easier...
Gaston