I know I'll get flamed for this so I'm wearing my asbestos shorts!! The clutchless shifting debate is as old as motorcycles.
With all due respect, and from a mechanics viewpoint I'll place another vote for using the clutch to shift. If I was riding someone elses bike and racing for a big trophy then its different, If its my favorite bike the clutch always gets used, especially for downshifts. I can nudge the clutch as fast as my foot can shift, so there's no downside to it. Clutchless shifting is just lazy. I never have this argument with a mechanic, its always a customer who never looked close at a transmission.
It absolutely does round off the gear dogs faster. However, transmissions are very robust and chances are it may be a problem for one of the next owners so the abuser goes on oblivious to its effects. Besides, most bikes never see high mileage, or something else does it in. Kinda like smoking,.. there's no apparent side effects while your doing it, and most people die for other reasons anyway, but its still unhealthy.
I will acknowledge that a careful clutchless upshift with a perfectly timed throttle interuption can unload the gears and work with no consequences. This rarely happens perfectly so the gear dogs usually end up crashing into eachother to some degree. We just don't hear or feel it. Its almost never possible to downshift in a way that causes no harm, and again, its just not any faster!
Transmission wear may be a small thing and anyone can choose to do clutchless shifting if it makes riding more fun for you, but just like smoking, its not harmless, just a calculated risk. In my mind its a little unethical to sell a bike without mentioning it or ride someone elses bike that way without asking.
My favorite saying,.. "Don't confuse good luck with good practice" luck can run out.
End of sermon and back to your regularly scheduled programing...
