Haha, you may be right conerning the speed-increase when considering harddisk accesses because of swapping and graphics performance (even if the mini isn't teh grafix b0mb).
Concerning my remark about Mac OS: This wasn't intended to suppose you said it was the ultimate OS, it just means I think there are a lot of deficiencies in its concept and execution.
I think the duck-typing illustrates my point however, even if it was poorly phrased before: If you don't know what you're doing because you don't have to, it's hard to find out why something fails. The lack of necessity to declare what object-type you're expecting for a method y (which you can simulate that in other languages than Python as well, by just requiring an Object instead of a more specific class)* in the case of duck-typing can leave you in the dark why the method x of the argument couldn't be called inside y. Equivalent, if you don't know that this-and-that thing causes problems with sh but not bash, it's really hard to debug a shell programming problem that could arise if the OS thinks you're using sh. In contrast, if you know you use sh, it's obvious what you can and cannot do, and it's easier to google for problems.
About Ubuntu: As far as I know, the shells are still specific. Had to reset the shell for my DB2 user to bash, because it was only using sh.
*: had to scrap that, it's not true. You cannot use specialized methods of an Object-class object without causing an error message already before runtime unless you cast it.