If there's less steel inthe blade, it's gonna be weaker. Radiousing only minimizes the loss of strength. However, if your lock gives out before your blade, I guess it doesn't really matter. There are other reasons why I will never own a folder with blade cut out.
Sometimes I use a folder to assist my fixed for skinning out game. Especialy in a large aligator where you have to reach up into the guts and lop some internal organs free(I don't know all their respective scientific names, but they're pretty gross). Anyway, a buddy who was helping me once had some Spyderco that had the charachteristic cutout, when he removed his hand from the body cavity, there was all kinda gore in the hole. Yuck! Sure, it's easy to clean out, but it was just weird somehow. Like the guts permeated and infected the steel or something. More mental than anything else, funny thing is I'm not squeemish at all...
Oh yeah, and cutouts, along with thumbstuds, are completely unneccesary.