Cost The technology to benchmark DigitalTF against is IoT. The Internet Of Things comes at a high cost: Even IoT companies do agree that the total cost of connectivity will never be below 8 Euros/node/year. Most analysts agree that the total cost is very likely higher, up to 40 euro/node/year. This will add up when more and more devices are congestion managed.
This may however be the least of all problems with IoT.

Hacking and speed An IoT network is easily brought down by a simple DOS attack or even spread spectrum RF. Imagine bribes where criminals blackmail the grid operator on very sunny days. It will be easy for them to overload a distribution substation. DigitalTF, like Ripple Control, is unhackable.
Latency of IoT is another issue. A DigitalTF telegram takes only 1 second. Such speed will not be achieved, and certainly not guaranteed, via IoT.

Complexity and maintenance Last but not least: The complexity and maintenance of IoT solutions. Trained ICT personnel is required which simply is not there. From the Smart Meter grid operators have learned the complexity of a network and the relation with a provider. 2G is already being phased out! 2G Smart Meters are being replaced less than 2 decades after they were installed.
Commissioning is another challenge. With DigitalTF, any device automatically knows to which LV grid it belongs. With IoT solutions this will need to be programmed.