1) False. Software screen switching is easily instantaneous. If you literally have two front buffers which, you must for a dual screen setup... there’s no reason you couldn’t flip between them at the refresh rate of your monitor (which is ridiculous but doable).
Workspace switchers that run on shitty old X can be and many are effectively instantaneous. Not sure about Windows, but I assume something exists.
There’s more to life than Mac OS X.
3) you can still have a spatial layout of workspaces even with one viewport.
Well I didn’t say multiple screens didn't serve a purpose, did I?
Having said that, is there any good evidence of a fair comparison of dual screen vs a fast switching single screen. Most Mac and Windows setups make switching so tedious and slow it’s pretty obvious that dual would be more productive.
I would not be surprised that a truly friction minimized single screen setup (total switching latency from input to display <100ms... which is technically easily achievable (and done in many special purpose devices... just not in PC software).. and ergonomic switching key would approach dual screen in productivity. I mean, this is the typical setup I and many others use on a Linux laptop for dev work. By the time someone gets MC on OS X up, I can literally switch “screens” 3 or 4 times.
I enjoy a multimonitor (4) setup, but I’m not about to trade off battery life and space for it on the road.
Frankly it’s just easier and cheaper to buy a second monitor with state of the art, for most people. I get that. I use OSX and Windows too.
Also, I would expect more than 2 monitors to increase the gap.
There’s more to life than Mac OS X.
3) you can still have a spatial layout of workspaces even with one viewport.