Hello, SCX Digital Fans,
just found that thread and thought to answer your questions here.
My homepage
www.slothobbysolutions.de was already mentioned in the thread below.
As the scxworldwide has been closed down, some good threads are unavailable now.
Therefore I thought to start posting the answers of your questions here.
RMS 
is the standalone PC interface for SCX Digital which went through some development since it was released in 2007.
RMS 
was especially made for SCX Digital to support the great system. PCLC is the "mother" of
RMS 
and developed from the same programmer.
From a SCX Digital functionality point of view the software is the same and if SCX Fans asked me, which one to choose, my answer was always, if you are a club, having more then one system, performing championship racing, then PCLC is the right choice for you.
If you want to keep it very simple, remain the SCX Digital touch, then SCX D
RMS 
is the right choice.
Personally I am using
RMS 
only as the main functions are available. Especially the Telemetrie functionality is the same on both systems.
The interface itself went through some development stages as well. From an external black box to a small more reliable solution with USB connections which can be build under the track.
We were a team of 3 fans of slotcarracing (Guy, Ole and myself) , got to know each other via Internet only, build up a good team and now are good friends, which are still addicted to the solution and the product provided.
If will try to check the forum on regular basis and if you have any questions about the system, feel free to visit the homepage or ask a question in the thread.
I am using SCX D now for over 5 years and it is still my favorite system. Looking forward to the news things which will hopefully come out.
Best Regards
Sven