acejavelin,
Since we have started selling the Mitel Phone Manager we have sold quite a few of them. Of course we didn't start until 4.3, but most customers like the added features they get with it.
I am not so sure about Mitel requiring it to be sold with the 6900 sets to get all of the features, as not all of our customers bought Phone Manager, but I think it is their way of adding features without making too many changes to how the MiVO-250 functions as a standalone system; much like Intelligent Router.
I do like the fact that they will be adding some resiliency functionality in the future for the 6900 series phones which isn't even a possibility with any of the current offers. Maybe they will start making the MiVO-250 more of a SIP server than the MiVB or MiVB-X servers; who knows.
Thanks,
TE