I wrote a little program that will switch the active version of LumenRT between LumenRT 2015 and 2016 (Connect Update 1). You can download the program here:
Just place the program on your desktop or where ever and run it. It requires that you have both LumenRT 2015 and 2016 installed.
After you install the plugin, in the "ProgramData\e-onsoftware" folder by a "LumenRTReg" folder and need to copy files to the "e-OnSoftware" folder in the root directory, to run properly. This question is only for SU2016 version, SU2015 is no problem.