Good article - that guy nailed a lot of points. For my company, coming from the data world has made this easier on us. Plus with our large voice and virtualization lines of work it is a great fit. My problem now is that the majority of our enterprise voice work is Cisco. Of course Cisco won't be far behind on this one....
I personally do more Cisco than Mitel work these days for a variety of reasons - that said, I'm still a fan of Mitel and work to promote it in our business.