Contrarian, and orthodox, view:
Much of the time you CAN shift up without the clutch. Most of the time you CAN'T shift down without it without grinding the gears. And it takes repeated good luck/ and or a lot of practice to do it well, especially when shifting down. And, regardless of your skill, there are those inevitable times when you botch it. You won't have to guess when that is, the bike will scream your mistake at you.
Remind me not to buy a used bike from a clutchless shifter. Wait a minute, isn't he the same guy that says its good to keep her at the red line as much as possible? That the rev limiter is a stupid, conservative, useless addition? And that break-in is a myth? And that almost NOTHING that the engineers at Triumph, or any other manufacturer for that matter, designed is really what should have been designed? Like a clutch, for example.
Having raced for many years, I am unconvinced that the throttle hesitation required to sync the gears when you speed shift without the clutch is any faster, and may in fact be slower, than shifting up through the gears while holding the throttle wide open and feathering the clutch as you snick through the gears. Of course if you don't give a ***** if the gears grind now and then, well, go for it.
Save your confederate dollars, boys, and your gears, and use the clutch. Or get a scoot with a variable speed tranny.
Monte