No doubt it can be done, and will find the next gear. Will it damage or harm the gearbox, likely no, but it will cause increased wear and rounding of the gearbox drive dogs.
To reduce wear and add longevity, it is best to at a minimum unload the gearbox with even a partial pull of the clutch.
As a kid racing dirtbikes in the 1970s, it was common to upshift, even downshift without using the clutch. When you open a gearbox up and see the rounded dogs, which requires replacement of the worn gears, it is disturbing.
Since the 1970s I prefer to use the clutch whenever possible. Not pulling the lever fully to the grip, simply enough to unload the gearbox. Learning this way of shifting found it is faster to not back off the throttle to shift without the clutch, but rather to leave the throttle pinned and allow the rev limiter to control rpm, while you partially pull the clutch and take a gear. On the larger displacement bikes, the rev limiter came into effect less, since the same technique was done at partial throttle settings.
As for a Spyder, since it is accepted that the gearbox is the same for the SE and SM, and the SE electronically cuts engines power to shift gears, the question becomes, does the SE also cycle the clutch during shifts?
