Carefully done the notched blades should be fine.
Personally I'm not a fan of the mulching blade thing, but what do I know?
I did this with stock blades, and like the results:
And I have always bought GRAVELY blades.
Thanks, DJ.Maybe it's just me being paranoid, but I'd be terrified to run the notched blades Mikey. I can just visualize a stress crack starting right in the corner of one of those notches and a blade failing catastrophically. Again, maybe I'm just paranoid but I've got the heebie-jeebies thinking about that one.