My Drake does not have Sani Gloss. When I bought it in 2005, I asked about Sani Gloss and was told that it was overrated.
My Cadet 3 has its own special finish and rinses better than than my Drake; that is, stuff rarely sticks to it.
I would say that the salesperson who advised against the Sani Gloss probably did not know what she was talking about, and that a Drake with Sani Gloss would probably rinse as well if not better than the Cadet 3.
HOWEVER, the Drake without Sani Gloss works better than anything that has been in that bathroom (and there have been many), and it's a keeper.
My advice: if you have the option for Sani Gloss, go with it.
achutch