The need for current transformers is only based on the currents you are expecting and the max current the devic can measure directly. It does not influence the precision much, just the range of measureable currents. If the price difference is not much, I would opt for the ethernet version, it is less hassle to get running and you can use it more flexibly. There will be no quality difference just a more comfortable use and no need for trancievers or gateways. For the Siemens energy meter you have a lot of option to configure it, but if you purchased one you cannot reconfigure anymore, so you can select the comms protocol but then you are stuck with it. I somewhat agree with @DanielH about Node-Red, but if this is a lab, I think Node-Red could be a good first option and see later if you need something more robust or higher throughput.