I was thinking of subbing some whole wheat flour for part of the white flour. Has anyone tried this? Thanks!

I routinely add a third of the flour as whole wheat white in anything I bake.

I commonly substitute 1/3 white flour with whole wheat pastry flour (make sure it's specifically pastry flour, not unspecified or bread) in scones, cookies, pancakes, etc with no issues with texture or changes needed in the recipe, and I particularly like the flavor in scones. I actually would advise against letting it rest, since it's best for the butter to stay cold. I think the extra moisture absorbing properties are much more dramatic with bread flour and in the case of scones you're not really hydrating the white flour first either.

One rule I heard somewhere that I frequently follow is, if I want to add a bit of non-white flour/meal to a cake, scone, muffin, biscuit, cookie, etc. recipe, I just sib ¼ of the flour, by weight for the alternative grain. It's always worked for me. Any more and you alter the final flavor/texture of the product. That might result in a better scone, but there's only one way to find out. Play around with it, the worst case scenario is that you learn something.

Go ahead! You may want to add a bit more cream--depending on the amount of the sub--as whole wheat absorbs more moisture than AP flour. Let the dough sit for 5 minutes before shaping and baking to let the whole wheat hydrate and to prevent a dry scone...you can always add a bit more cream at that point if needed. The dough should be soft and more to the wet than the dry side.

I can't imagine why you couldn't. I do it all the time. It will no doubt make them taste better! ;o)