The harder the pad, the faster your rotors will wear. I'd rather replace pads over rotors, any day. The only pads I've had negative experience with, are Kevlar. They have a severely delayed response under wet/cold conditions. When wet, I've had to intentionally drag the brakes for a tenth of a mile, just keep some heat in them.
I am one of them that rarely use front brakes unless I am needing to so I cannot wait to see the difference in pad thickness next time I put tires on. I just put tires on a VTX1800 that also had no rear brakes but plenty of pad. Had to look up the bleeding procedure for the rear so I knew which bleeders to do on the front for the rear brakes. I guess the FJR will be the same procedure so I need to look in the FJR SM for directions.
I used to do similar on my YZF, attempting to even out tire wear and keep from having to replace the front pads. I still always applied the front, just not nearly to the degree that was intended. I quit in part because the front pads last basically forever; also because the rear simply wasn't designed for it. The pad carrier ("bracket support") was taking actual damage, as well as accelerated wear. I was going through pads like a thick chick on a period cycle. In addition, the front I found, were just as easy as the rear to replace. Aside from tire wear, there really wasn't any benefit. Braking normally and occasionally, intentionally HARD
, also helps keep those skills sharper. That way if the situation actually warrants it, mistakes are less likely to be made.