Well, the problem with the Ears should be pretty apparent: you're paying for an onboard contact mic that's not useful for the purpose you have in mind here. I also feel that putting a contact mic in a patchpanel is a pretty bad idea unless you can disable it somehow to avoid lots of extraneous clunking and banging around that'll get into your signal path. It might be cool-looking and all...but it's not the right tool.
Basically, you're talking about using this sort of thing: https://reverb.com/item/2274010-2x-piezo-elements-for-drum-triggers-contact-mics-fast-shipping , which is a piezo sensor that can also act as a contact microphone. These need a good bit of amplification to be musically useful along with the other parts of the needed module, namely the envelope follower. My concern is whether the Ears's input preamp is capable of the necessary level of amplification...if it's designed for line-level input signals, it might not be. But both my Dean Markley and John Pearse contact mic/pickups do need that, so I'm basing my observations on those. There are a few that have high outputs (AKG makes one that I've used before to amplify a chalkboard through a Peavey stack via its guitar-level input), but they're not piezos.
And I should note...the next consideration is going to be what you plan to do with the envelope following function, since there's no VCAs here or, for that matter, much else that the envelope follower can interact with. And if you're planning to use this with drums, that consideration is key.