I suppose you're aware the DM6 is only the gauge part. It does not include any sensor modules such as WBO2. PLX and Innovate are both solid units in my experience - when installed or connected properly. Takes you pick, but I strongly suggest a recording unit you can play-back with, or one that has an output to a laptop or smart phone to record for later viewing. You're just too damn busy to watch a gauge while driving, let alone try to see all the little bits of info and how they relate.
The PLX one I was reading about is a complete AFR kit for around $200. I'm more interested in this one because of the smart gauge and it is all modular. I will need to add a vaccum/boost module to the same gauge for my turbo VW buggy project so it is really flexible. Gauge space on the buggy dash is at a premium.
I don't think I really need anything more sophisticated than this for my stuff.