I'm running with a set of Murph's risers plus his wedges - not sure if that counts as stacking or not, but the wedges do raise the grips a bit on top of the gain from the risers. The angles and height work really well for me at 5'10". (I have short legs for my height, average length arms - probably would be 5'11" if my legs were proportionate to the rest of me.) I have some trouble with carpal tunnel and the wedges take some of the compound angle out of the grips, as well as putting them a little farther up, a tad closer together, and a little farther back compared to the risers alone. I don't notice a handling difference, or at least I don't any more, seems like it felt a little different for a while after I installed them last year but now it feels like the bike came that way.
Oh, and this combination doesn't require any mods to the brake or clutch lines, at least not on a non-ABS 2009.