3R DCC is very interesting. It offers better sound and is not proprietary to any one manufacturer. There are two major downsides: (a) the cost of converting a large loco inventory and (b) the incompatibility of Pullmor motors with DCC decoders currently available.
The curious twist on this is the Blunami product, which can provide Bluetooth control of a suitable can-motored loco without a DCC power source, yet incorporate the normal DCC decoder functions. Most implementations of this, to date, use "dead rail", e.g., rechargeable lithium-ion batteries in the loco as the power source.
My Blunami card arrived today. It will be installed in a Weaver Baldwin Sharknose diesel. The key to making this work on 3-rail, AC-powered track is to determine the degree of filtering and regulation needed in an onboard AC-DC converter (glorified rectifier), as the Blunami card cannot be powered directly from AC track voltage. I will examine this in detail, since Soundtraxx could not provide me with a maximum 120 Hz ripple specification for the card's power source. If my pilot project is successful, I will probably convert my several pre-TMCC/DCS dual-can-motored diesels to Blunami/DCC (well, to the extent that their motor stall currents do not pose an overload problem for the Blunami card). My two can-motored steamers' motors have a stall current well above the Blunami 4A limit, so they aren't conversion candidates.
I'm also looking at Blunami in the context of my club's S-gauge travel layout, for control of American Models and S-Helper locos. Motor stall current is far less of an issue in S-gauge.