Both have been widely discussed and met with approval. Admirable as the work on using recursive assertions is, I am afraid that Marcel Satchell has a point when he notes that they can't be fully satisfactory given the semantics of Eiffel assertion evaluation. In that case there will still be an Eiffel 3 version of the class, which will have identical semantics to the ELKS version except regarding assertions. This should be acceptable. But we need to discuss the merits of the competing approaches on substance, not dismiss any of them on the basis of its current unavailability in some implementations.
Current availability is a criterion, but a secondary one.
So I would like to suggest that we discuss the various approaches on the merits, not on the basis of short-term considerations. The short-term aspects should take care of themselves. The ELKS ideal of a standard that has official status and perfect assertions may take some time, sweat and arguments, but that does not prevent compiler implementers from coming up in the meantime with a temporary version of the class that benefits from the ongoing work and is practically portable even if temporarily imperfect. For example, you would call resize before putting elements in the array. Run-time takes care about it.