How easy/hard would it be for someone with basic soldering skills to replace the alphanumeric switches on a qfr with mx clears?
It's all relative, but I find switch swaps to be trivially easy. Get a good chisel tip to maximize the contact area and turn your iron up to 650 degrees or so. Once the solder is molten, use a solder sucker (a wick works too, but isn't as convenient imo) and repeat. Once the solder's been removed, I pinch in the two tabs on the top of the switch and apply pressure to the plastic peg below. If you got all the solder, the switch pops right out. If you notice that there's a bit of solder left in the through hole and it's preventing removal,
don't just fumble around with the iron to try and melt the remaining solder since you'll run the risk of lifting the pad if you apply too much heat. Instead, just apply flux to the area (optional, but I've found that it makes things easier for me), re-solder the switch, and then try sucking/wicking out the solder again. It goes really quickly once you've gotten into a rhythm.
Installing the new switches is super fast. Just snap the new ones in and then solder the two pins on the bottom.
