I'm pretty curios about: why SI develop team choice S key for interactive mode? What is the presumption advantage?
I come from Modo/Silo, and SI original interactive mode was a little trauma (and cannot map the infamous and useless Z zoom key...)

Im interested about this too. You can say one key used consistently should be more centered than towards the edge of the keyboard so you can get better coverage but it still makes no considerable difference than having your thumb on alt key for example.

Guess selection tools just needed an extra key for loops/rings. Its not a bad solution ether, its just hard to get used to when almost all other major software uses alt/space for navigation.

Oh well... system is as flexible as you like. Not many apps allow you to easily change things around if it doesn't work for you. SI, fortunately, does.

I have some doubts about: the ALT+MMB loop selection can break modelling workflow (you must deactivate your selection manipulator (move, scale or rotate), then select your loop and after this reactivate your manipulator. Nothing so terrible, but a nit slow IMO.
Don't how is loop selection (or other interaction) in Maya Interaction Move

About S key, agree, it is more central in your keyboard, but it is identical to other keys, instead Alt key is bigger and more easy to find by touch.

i always loved the S key, also i'm a "right click property" fan user, i love software that uses the right click on things and the properties of that thing you are on pops up.
i always hated maya spacebar navigation for this reason, its too intrusive to do every task, S and alt+right click is just great to me

I have no idea.

But if I were to hazard a guess, I would say it's probably because Softimage was basically the only game in town back then. So Alt-Left/Middle/Right mouse navigation was yet to become a standard. You can see the same thing in Ye Olde Lightwave, which goes a long way back and has its own funky navigation method.

Just a guess though.

P.S. The S key navigation and sticky keys are teh awesome.

S key doesn't work for me at all, I have to use the thumb for navigation, force of habit.

I put nav on the spacebar, so panning is the same as in the Adobe apps.

Using the Alt key for navigation would be ok but it makes my thumb ache after 5 minutes of modeling because it's too far to the left.

I like the S key, in any case I think, after take habit, all navigation type is good.

Only strange to me this preference (why not G key, i.e. is more central). In XSI you can cage all the button (I find how remapping Z key!), but not the mouse button.

Wha is the LW navigation button? Is not ALT key?

I do the same as rray. I put nav on the space bar. It's close to alt so it doesn't completely mess me up for other apps that use the alt key and it feels natural to me.

I use ALT key navigation.
I put my selection tool and loop/range function on Q key.
So when I hold Q I get loop/range function, no need for another key.

TAB for tweak tool,
CTRL+TAB for prev/next manipulator,
SHIFT+TAB for view plane pivot transform tool .

Pretty handy and easy.

S is comfortable for me, since my hand is used to that placement with FPS shooters... WASD...