I drove manual car for a long time but never tried to switch gears without clutch.
Question: given that clutch-less shift is executed properly, does it take a toll on transmission in any way? For example: does clutch-less shifting reduce life of synchros?
It is straightforward to do this without any wear to your synchromesh, but it takes a lot of practice, especially when downshifting as you need to match revs accurately. Learning to heel and toe correctly will help you a lot here!
You should never need to race the engine, as you should be using the same rev range as you would normally driving the car!
Question: given that clutch-less shift is executed properly, does it take a toll on transmission in any way?
See Rory's answer: it is possible to do properly without wear. It is difficult to do properly every time.
For example: does clutch-less shifting reduce life of synchros?
While you are learning shift clutch-free, yes, you will beat the hell out of the synchros.
My advice is to learn how to properly heel-and-toe using the clutch (and actually double clutching). Become an expert at using the clutch properly and then decide whether clutchless shifting is for you.
Full disclosure: I never shift without the clutch. I don't drive a dog box in competition and don't see a good reason not to use one of the pedals available to me. I've worn through the floor mat in two places trying to become better at heel and toe-ing, though.
I had an old T5 I could shift beautifully without the clutch but the motor had to be screaming (somewhere between 4 and 5 grand). At normal operating speeds the transition just wasn't fast enough and the gears would grind.
I've never seen a tranny that would tolerate clutchless shifting under regular conditions without some major gear crunching.
