Or again, keeping 7 stages FLSS by merging BF and DL. I know you didn't agreed to it earlier, but just let's imagine it.
A character may prefer one stage over the other (as they have differences), but if he likes the layout he will feel comfortable on both. Inversely, if a character hates one of those two, he will probably not like the other one either. You said it yourself, the two are kind of redundant and we do not want them both on a 5-starters list.
So in regard to game 1, it changes nothing. A 5-starters list without DL or having BF+DL considered the same, in both cases DL is unavailable game 1 (unless both players explicitly agree to it of course).
Now for later games, the only thing that changes is that the winner is not forced to use two bans to get rid of one general layout he does not like (IF the ruleset allows two bans in the first place, otherwise he will probably be taken to the non-banned stage of the two, which kind of defeat the purpose of his ban). If the winner prefers to ban another stage, then fine, the loser is still free to take him to DL if he wishes since he chooses the stage, similar to how we proceed today with Miiverse and Omegas.
The two methods (5 or 7 starters) are functionally almost identical, the only change is IMO a good one, and all the while keeping an (IMO again) superior method which is FLSS. Right now my ruleset (who hasn't included Umbra yet) gives two bans (no DSR) to the winner, but if I end up merging BF and DL it won't bug me to go down to 1 ban.
Edit
Yikarur
: I always thought the the winner's bans lasted only one match, not the whole set ? (Also why keeping the DSR ?)