removing the button... seems a good idea, but I'll report you if people don't like that when the map has come out.
About new features, maybe another breakable passageway which connects the middle of first part with the middle of another part. Hard to explain...
Brackets = spawn
D = Breakable passage
|| = narrow space in the middle
a = new feature, "a" is the breakable among the unbreakble wall. Simply, on both walls which are unbreakable, there is a 2 tall x 1 tunnel which extends to the direction of the wall(either < of >) then connects to the other "a"/tunnel.
Or maybe glass ceiling with skybox outside, to let sunlight in. Just to make sure, at the middle of breakable passageways, players can't go through the narrow space unless they break some blocks like in the original breakit.
Finally I've got the layout based on your layout
Red spaces are the new breakable passages.
The entrance should be 2 tall and 1 narrow(blocks), while the inner part of new tunnel can be 2 - 3 blocks narrow. Note that It's a tunnel, not a breakable passage. So when you've got into that part, maybe the breakable part is only 1 block thick(entrance).
PS : just don't forget to add a text inside the map which says original idea by ne0nfire and blablabla by you.