This factory RLS pickguard acts like a microphone diaphram producing high frequency feedback when playing at significant volume/gain settings, much like the old Telecaster bridge "ash tray" did. It also interacts with the pickup causing distortion of the magnetic field. On stage, I usually sit where I can reach the knobs on my amp. NoCanDo with that pickguard. At first I assumed the feedback problem was just a cheap pickup but we know what "assume" gets you.
My discovery process is in this thread: viewtopic.php?t=365511
The easy fix is a non-ferrous pickguard. I got mine from wdmusic.com which has a good selection of colors/designs for the RLS1 (I have NFI). This is the biggest bang/buck change you can do to improve the sound of these things.
Not satisfied to just fix the problem, I had to investigate. I love science experiments. techno-babble follows:
I put the factory pickup on my basic one-string stick steel guitar and measured the output voltage with and without the steel pickguard. I used an E-bow to achieve consistent uniform excitation of the string.
No pickguard = almost pure sine wave.
With pickguard = harmonic distortion (aka Timbre/tone if you like it
When the pickguard is struck, it "rings" like a chime. This also happens if the pickguard is excited by the guitar amplifier (i.e. feedback). Note: All of these measurements were "acoustic". No amplifier was used, so no feedback possible. Scope setting 2mS/Div - 5mV/Div
I took the RLS out to a local blues jam last night and it sounds great. It's going on the gig tomorrow and beyond. Granted, it now has a Seymour Duncan humbucker which is mo-better. I don't plan on doing anything else with the original pickup but I would assume
it's just fine.