I like the 500 series concept. I bought Slate VMR when it first came out. What I don't like is paying for stuff a second time. That's why I stopped using Slate digital Trigger and bought Addictive Trigger. Addictive Trigger allows the use of samples from your Addictive Drums collection while Slate Digital Trigger doesn't allow you to use the samples from SSD.
I would love the ability to use my T-Racks, Syntronik and Amplitube processors in that environment but not enough to pay for them again. With all due respect to IK, that's a fair price for an awesome product (MIxbox) if you haven't already purchased these processors in the past.