The Slate phones are nice on their own - I have been a user since the inception, about 5 years now. Always impressive. I had the phone replaced once (free of charge) as 100s of the earlier sets had small piece of plastic that would break. They replaced them with metal. I have used the software with HD600s as well with success, though prefer the VSX phones. The MDRs would not work well.

The VSX software and the included rooms are 100% sufficient for any mix situation, which is to say no other rooms or purchase will ever be needed. Any add-ons for purchase came after 2-3 years and attract the users who need all the latest missing silver bullet....

Like most users, it is just one of many references I use, and not always. But it is a really good one. Learning curve is small. Recommended.