1977 RD400 Cafe Racer conversion project

From what I recall of the RD350 which is the closest thing I ever rode or worked on to your bike, they are bone simple when it comes to electrics. My current ride is the polar opposite and has one of the most complex electric and electronics systems ever devised. From what I read on the M unit thingy it does away with relays and I can only assume that it does that by replacing them with solid state electronics. I just took a look at the wiring schematic that I believe applies to your bike and the only relay I cold see was is signal flasher relay. I was curious what the warranty for the M unit is and was unable to find any expressed warranty, just a form to request for service.

I'm with the woodsman on this one, you could probably hire a professional electrician to wire your bike from scratch for the cost of just the M unit and I'm not seeing that it does anything really special to address your wiring problems, it centralizes your wiring connection wherever you chose to locate the M unit and there is nothing to stop you from doing that same thing now, instead of using the traditional headlight shell location.

LED lighting is very cool looking and all that, but realistically anyone who choses to retrofit LED lighting to a 40 year old motorcycle currently comes under the heading of early adopter for that technology. Same as with lithium battery technology. People who pursue bleeding edge technologies are paying a premium to prove the worth of technology that is still in it's relative infancy. That generally spells big bucks and high risk. It might be the greatest thing since sliced bread or it might be a money pit, but it certainly won't save you any money off you household electric bill. Keep us informed how it all turns out in 5 years time.