I suppose that for some things, yes, I have seen a noticeable improvement, such as when making breads. Kneading dough for long enough can take a while by hand and I tend to stop before I should. Tossing it in a stand mixer does all the dirty work for me, though, with very little effort, and my breads have been noticeably better since then.
I find that my bulk cooking results are better, too. Using a mixing spoon for small cakes, brownies, etc, is sufficient usually, but if I'm doing more than one batch at a time, they mix much better in my stand mixer and I don't have to worry about dry spots getting missed.
When you say "hand-blending" do you mean with a spoon with with a hand mixer? If it's the former, then I recommend getting a hand mixer at some point to test out the difference yourself. You can get them for $10, so the price isn't crazy.