Please be sure to provide more in-depth feedback. GranteedEv did a nice job with his writeup but it is always nice to get additional opinions.
I can provide some preliminary feedback in regards to comparison of my DCX. It's an issue of trade offs.
The DCX ultimately is going to be a more flexible unit. For starters you can't sum input1 across all outputs on the MiniDSP. The actual flow and routing functions are the same in approach but ultimately MiniDSP not as route-able.
The DCX has the capability to store and easily recall presets. I had four:
HT, Music, House Curve-HT, House Curve-Music. The MiniDSP you have to have a computer connected.
In short the MiniDSP is PERFECT for HT Use. You can import REW configs. That is PRICELESS. The DCX is going to my bench for an upcoming 3 way active design that I want to do from scratch. Each one will be able to play to their relative strengths.
I am just waiting for the MiniDSP to start showing up in some ID speaker companies sub woofer offerings. You should be able to tweak a multiple sub configuration in 30 minutes with REW and the MiniDSP. My local AV firm has never even heard of either.