Are Type V forged?? When you get in the 20 inch rim range, one usually reduces tire profile to offset the increase in diameter. If you have potholes where you live, the bigger concern than scratching/curbing a rim is bending one IMO.
I have hit many a pothole in my life, most of them with my HRE's and have not scratched or bent the wheel. This has been with 20's and sometimes the tires are 25 series in profile. HRE's are forged and are stronger than cast wheels. This doesnt mean they wont bend but it takes much more to do it.
As for harshness, there is always an increase in road feel and bumpiness associated with the decrease in sidewall. For me the tradeoff is minimal but the gain in looks is huge.