Prior to Royal TS I used to use SecureCRT and found it convenient to transfer and receive files quickly using Z modem.
for our file transfer implementation we are using a 3rd party component which currently doesn't support Z modem. There might be a chance that the vendor support that in the future. If that's the case we can look into it and support it in Royal TS as well.
Sorry I have no better news for you at the moment.