I don't know about the additional remote functions working on the Z5, but I can say that the M5 and the Z5 are not identical otherwise. The M5 has a third scrubber brush that the Z5 is lacking.
When Brushpup comes back to the house I'll beg him to bring the remote again so we can play more.
Arrriiighty, I'll remember to do that. (Hopefully)
For those with the Z5, have you noticed diminished wall climbing? When I first used mine, it went right up the wall and did a great job scrubbing the water line. Now it does not get that high up the wall at all.
The only time I've notcied any diminshed climbing is when the filters (spring or fine) are extremely full, but that's it.