Yes, I used Scott's service roughly 10 years ago for what is now my son's 2005 e53. I had problems with rear window relays - he did a great job and they continue to work fine to this day. Have not had any interaction with him since, but back then he responded promptly to either an email, or it might even have been a phone call.
Having said that, I am now aware that removing and replacing relays on PCBs (printed circuit boards) is not that hard - provided you have a solder sucker gun. I find the
inexpensive spring loaded solder pump suckers are tricky to use - you really have to use them quickly before the solder cools down and hardens again. On the other hand, a desoldering gun with on board suction pump makes it much, much easier. Of course,
they begin at around $120, though a really, really nice
Hakko desoldering gun (which allows different tips for different situations) costs more like $250. My philosophy is that tools are free, and a one time use on your GM3 will pay for the tool. There is definitely a learning curve to it, but it's a very useful skill to acquire. I have since used my desoldering gun to fix a coffee pot PCB, dishwasher PCB, garage door PCB, oven timer/relay board PCB, capacitors on TIVO units, stepper motors on GM speedometers, stepper motors on Mastercraft boat instrument displays (oil temp, speed, voltage). Honestly, if you have a desoldering gun the hardest part is maneuvering through the websites of Digikey/Adafruit/Mouser to find the appropriate relay or capacitor. Of course, if the idea of learning/doing that is too much, send it out to Scott. I'm confident he will do a good job.
Good luck.