Not sure were you got your numbers but the abbreviation "SEC" was used during the years when Bill Potter owned the company. "CSY" (Carribbean Sailing Yachts) was during the 80's. I think I may have read that CSY over built their boats. They were around for one year and built only the 23 and 27 models.
As far as the ride comparison goes....there is a very big difference due to the difference in size of the two models. The 23 sf is a very large boat when compared to the 20sf. One thing that I can assure you is that you will like which ever one you get
strick