If you head on over to the S forums you'll see that there are numerous threads about bad ride quality, regardless of the setup. I had 19" wheels and air suspension, supposedly the smoothest option. I sold my S a few months ago partly because of the horrible ride. I have a 3 reservation so all these posts about the 3 ride are concerning. If the ride is anything like my S, I won't be buying a 3. From my experience, the ride quality is hit-n-miss. I had several S loaners that all had different suspension feel. Even the loaners identical to my car didn't have the same feel as my car.
In terms of quality, there is a big difference between a sporty/firm suspension and a rough/jolting suspension. A lot of the S owners complaining about their suspension have owned lots of different cars with lots of different suspensions and know the difference. I now own an Audi A6 with 19" wheels, same size as my Tesla, and while the suspension is firm, it doesn't feel like my insides are shifting out of place with every bump in the road.
I think my approach to the 3 will be to not buy sight-unseen, but rather test drive an inventory model for hopefully a day or two before I commit to buying it.