I have a Head YT IG Radical Pro, and I just added some lead to the handle to get a more HL balance.
I was shocked at the results. I added 10g under the grip, that's it. The racquet has quite a high SW in stock form (especially for something that light, 310g - spec). It was so much more solid. Everything I hit felt heavier. I did have some problem with depth though, it took a while to get used to it.
The biggest change was to my serve. When I hit it well, I could feel how heavy it was, however, my serve is inconsistent at the best of times, and getting used to the new weight didn't help, though it will come around eventually.
I wasn't expecting to have depth issues without adding any weight to the hoop, that was a bit unexpected. The plow through seemed to carry the ball further.
It doesn't sound great now that I've red my post, but I'm actually quite happy with the new feel. So much more solid.