Can I substitute both sugars (white and brown) with Splenda blend?

As I noted in my review, my pie got overbaked by waiting till center came clean. Would you agree crust needs to have foil on it part of the time to avoid burning, and maybe center should come out a little moist to not be overdone....it sets a bit later??

Yes. There is no problem with this substitution.

Since she lists it as a substitute for both in the recipe I think it'd be fine to do so.