Yes it could cause problems because this is a propcan subclass, so <code>&#95;&#95;getattribute&#95;&#95;, &#95;&#95;getattr&#95;&#95;, &#95;&#95;setattr&#95;&#95;, &#95;&#95;getitem&#95;&#95;, and &#95;&#95;setitem&#95;&#95;</code> are all changed.  Also because slots are in use, the special runtime methods <code>&#95;&#95;get&#95;&#95; and &#95;&#95;set&#95;&#95;</code> are changed also (this is reason for need <code>super_get/set/del()</code> methods).

However, since this is 'private' anyway, maybe better just make it a real private instance attribute (by defining it as a class attribute, then overriding it inside <code>&#95;&#95;init&#95;&#95;</code>).  Then you don't need to override <code>&#95;&#95;setitem&#95;&#95;</code>, and can just use <code>super_set()</code> and <code>super_get()</code> to access it.

Also, it would be good to have a unittest which triggers this problem, then the same unittest can confirm it stays fixed also :)