Sewnoma ... Today, I had to go to my Bernina dealer and they had the Q20 set up in a white table. All seemed to be pretty smooth where the leaves joined. Yes, there was somewhat of a gap, but no worse than I see with my dining room table. Definitely there was not a change of levels between the seams that would cause any issues with rulers being moved around. The table I referenced earlier was at a different B dealership, and in looking at the one today, I would say they were the same, just different finishes, as you suggested.
I took a look around to see if the tables are the same as what I have seen. From the not-so-great quality pictures, I would say they are, but with some uncertainty. (Note: I am in Canada, and sometimes we get different spins on the same products)
Here's someone who bought the Q20 back in 2015
http://bbquiltmaker.blogspot.ca/2015...-quilting.html
It might be worth your time to email her to see if her table has the same issues as yours.
If so, she might have some solutions .... or if hers is smooth, then, you have something for comparison before discussing further with your dealer.
I would be sure to exhaust all possibilities with Bernina before looking for alternatives.
Generally, they are good with their customer service, as they know how bad news spreads.
If you are not getting satisfaction/cooperation from your local dealer, move on up the ladder!
Good Luck! ...