I thought the same about the expense and weight comment. The looks of the stock exhaust was my motivation for changing it out.
Nothing wrong with changing it if you don't like the way it looks. Personally, I think the stock muffler looks fine, as long as the bags are on (mine never come off). With them on, it matches and balances out fine. With them off, well, it does look huge.
Shaved a lot of weight, looks better, sounds better,
Weight- on an 820 pound
loaded bike, 10 to 15 pounds is around 1.4%. Way more than the variation in what I put in the panniers from ride to ride. Looks- subjective, see above. Sound- subjective... stock sounds fine; don't need/want anything louder or "different" sounding.
and performs better... although, I don’t think there is enough gains to register on the butt dyno without the ECU flash along with it.
Changing the muffler does nothing anyone could ever notice, regardless of FI changes or flashing. Perhaps 2-3hp but only at 6K+ RPM at WOT, which is pretty meaningless. Now, if you wanted to change the headers and also go dual-pipe, and flash appropriately to match,
that has some actual performance significance.... but will also be a weight
gain and cost a hell of a lot more.
It really is just a cosmetic change. But, if that is what floats your boat, go for it!