Do you mean Current Transformers?
Does your emonTx have an ESP8266 either internally or externally, functioning as a Wi-Fi adapter, or do you want to use the built-in ISM band radio to get the data to wherever? If the first (or you add an ESP8266), then you can send the data by Wi-Fi onto your LAN, then to anywhere - emoncms.org or emoncms running on your own server (which could be another RPi). If you want to take the second option, then you probably want an emonBase, which could of course sit on your LAN to send the data onwards (as well as keeping its own database).
My colleague @borpin always recommends one RPi per task, so a RPi with the RFM69Pi transceiver would be the way he recommends, rather than running emonCMS in parallel with other tasks on the same RPi. Obviously a higher-powered server would be more capable of running several tasks at the same time.