I did comparison between RF part of XJT Lite (initial RF firmware) and X9D_2013 (v2.1.0 RF firmware) on D8 mode receiver.
I then compared XJT Lite (initial RF firmware), X9D_2013 (v2.1.0 RF firmware) and XLite-Pro (v2.1.0 RF firmware) on ACCTS D16 mode receiver.
In D8 mode there is roughly 6dB loss versus X9D_2013.
In ACCST D16 mode there is only 2dB loss versus X9D_2013.
It seems me that XJT_Lite in D8 mode is not very well designed and it is perhaps simply a firmware issue.
In my case I bought this XJT Lite to target my VD5 receivers on XLite-PRO which does not support D8 mode.
At the end I implemented a 'FrSky Taranis X-Lite 2.4Ghz internal Antenna' patch antenna inside XJT-Lite to replace the external antennafor compactness purpose.
With this modification I am loosing 6dB more :-(. Anyway to drive Indoor planes it is good enought.
To be honest I would have done better to buy a MPM non-FrSky module and would have got at least equivalent performance for equivalent price with the benefit of Multi Protocol.
Nota: the internal connector is IPEX-4 while the 'FrSky Taranis X-Lite 2.4Ghz internal Antenna' connector is IPEX-1. Thus I was obliged to add a RF adaptator IPEX-4/F to IPEX-1/M.