The clubs where I shoot local WB matches have used what some call "Mild Bunch" rules for a long time, in an attempt to get more participation - any SASS legal rifle, any centerfire 1911, 87 shotguns OK, no power factors. And, it worked! We had a lot more shooters come out than if we had gone strictly by WBAS rules. The new rules make almost all of that official & makes the double legal (which several potential shooters asked us to do, but we just offered to loan our 97s or 12s). If the intent is to increase participation, then the rule changes will likely succeed.
All that said, I have always used equipment & ammo that conformed fully to WBAS rules & will continue to do so. I have always enjoyed "old school" WB so why should I change?
Holler