A foot pedal is no less discreet and portable than an external mouse, and those are pretty widely used and accepted at coffee shops (it could even be argued that the external mouse consumes more valuable space than the foot pedal - the mouse requires lateral table space and elbow room, while the pedal is literally on the floor beneath your feet).
Likewise I know developers that bring external keyboards like the Kinesis in their backpacks to wherever they want to hack.
Edit: that being said, you're right that it adds up. I believe the author of the article also uses a vertical mouse. That's a lot of gear to haul to Starbucks!
In other words, one might feel uncomfortable being the only person in the coffee shop using a foot pedal because you don't want to break the mold? Seems a poor reason when the foot pedal could boost your productivity and/or prevent injury without adversely affecting your coffee shop neighbors.
And we evolve! :) Eg., it's been acceptable for some time to operate an iPad with an external keyboard at the local hipster coffee shops. I'd argue that anyone using a foot pedal at all is an early adopter - who knows what Starbucks' digital denizens will be using in a couple years? But we will arrive there faster if some of us eschew the lowest common denominator, even if we look funny doing so and have to haul around a peripheral or two or three.
Right, for example you rarely see younger, MacBook owners with the external mice. But when you find middle-aged folks with PC laptops, they are often using little travel mice.
It might be that Mac trackpads are a really good solution. For me, I try to avoid pointer devices, but when I do have to leave the keyboard, it's nice to only travel a couple of inches to the trackpad instead of a foot to the mouse.
I had my laptop pinched last week so I've been on a Mac desktop with a Mighty Mouse. The gesture control is so clumsy compared to what you can do with a trackpad.
No, I'll back Aidos up. I hated trackpads until the first time I used a MacBook. Apple's trackpads are just way easier to be precise with. I have no clue why. It can't be the software, because it's still true when running Windows via Boot Camp.
It is still an age thing. Old people have far worse a time on trackpads, especially on Windows.
I think much of the problem with Windows is in the Synaptics driver. On one Windows machine, I see 5-10% CPU usage whenever my finger's touching the trackpad. The trackpad on that machine works a lot better on Linux. On the other hand, some other trackpads work far better on Windows than on Linux.
One big difference between trackpad behavior on Windows and OS X is that on OS X there's always delay between when your hand touches the trackpad and when the mouse starts moving -- the first N ms are ignored. On Windows, it varies from machine to machine -- for example, on an ASUS machine I have, you need a certain threshold of movement and then the pointer catches up to what its location would be, but with others there's no delay.
Likewise I know developers that bring external keyboards like the Kinesis in their backpacks to wherever they want to hack.
Edit: that being said, you're right that it adds up. I believe the author of the article also uses a vertical mouse. That's a lot of gear to haul to Starbucks!