I have never driven on 20s, so yeah the guy has a point. But I have ridden in cars over the past 30+ years with profiles from 85 down to about 40. Could just be my imagination but seems like the lower the profile the worse the ride when comparing apples to apples. Of course you get used to it after awhile. Then if you change back to a higher profile, suddenly you discover how much quieter and smoother the car rides, who'd a figured. I have done this on several cars over the years, and in every case the higher profile tires rode smoother, but maybe did not handle as well.
Also sometimes you cannot avoid potholes. In many years of driving, I NEVER got a dented rim. Then one day diving less than 20mph, speed trap, so no Ricky Racer stuff here. I got into a situation where I was unable to swerve in the lane because some pita other driver hogged the road on the other side. It was dark and hard to see, but suddenly there was a nice juicy pot hole with no shoulder to pull onto. Yes I could have slammed on my brakes, and got a ricer enema from the guy behind me but I figured, I could make it. Wrong, Hit the hole with both tires on that side. Dented both badly enough to cause leaks. I drove that road every few days and the pothole was brand new so I would not have known before I got to it, to avoid it.
Tires are a compromise. High profiles are for good road feel and mileage, low profile are for good handling and looks. All the technical articles I have read in various auto mags seem to confirm this and mention the harsh ride on low profiles. Yes you can have a taller sidewall even with low profiles, but you do get limited on width by the wheel wells so in general you will be pretty close to the same width and only change profile. For handling you want stiff side walls, short makes it easier to do.
I just bring these comments up because they are things to consider as part a purchase decision. The LS is not known for cushy ride even with standard rims. So lower profiles will probably not improve things. But then we didn't buy the LS for a limo ride did we.
Like I said before I do like the looks of low profile tires and have owned a few cars with them. I enjoyed the tremendous handling improvements of the low profiles, but sometimes I missed the smooth quiet ride and until I got below 55 profiles, I never had a problem with dents.
Enjoy the new rims, but pay more attention to holes. The one that dented my rims was maybe 3 inches deep with a vertical edge because it was fresh. I think the sharpness of the edge has more to do with damage than how deep.
Good Luck,
Jim Henderson