Hi.
It's funny how similar debates happen on inkscape-devel (AI vs Inkscape) and gimp-devel (PS vs GIMP). I'd like to add Bulia's "look at what really is a common practice, not solely what AI does" -- look at what other free software packages do first.
I would prefer a slightly more obscure behavior if it was consistent across my free software toolbox rather than having each tool have its own. With a lot of effort you can unlearn workflows when you convert/upgrade to a new tool. But it's almost impossible to flip a switch in your head when you work simultaniously in GIMP & Inkscape and go forth and back.
At the moment, holding a spacebar in GIMP selects the move tool no matter what tool you are using (that would be object select as an appropriate Inkscape counterpart). Releasing spacebar will return to your previously selected tool. Does that sound more appropriate than panning on canvas? My opinion is that if Inkscape is not aiming to be "free illustrator" then yes. Not only is that consistent with GIMP's behavior, editing shapes and moving objects is probably 80% of what I do in Inkscape. Why not make it more convenient.
cheers