In this scenario you should still be using the clutch, but instead of easing it out you just drop the clutch with your blip. I do this quite frequently on the track. You can do it without the clutch but there is no advantage and very high risk of not timing your blip right and breaking something.If you time it right you can blip the throttle and rev match without the clutch. It'll unload the transmission to make the shift pretty easy.
I was only upshifting. I believe its not good on the gearbox to do it on downshifts. When I change down I usually rev match so its a smooth down shift. Ive done a video on that also.Maybe a dumb question but were you downshifting without the clutch as well? Isn't this hard on the clutch? I've done a couple upshifts by accident without the clutch.