[Android Software/Hacking General [Developers Only]] Almighty2:
Actually, if you had su in /system/bin, it's /system/bin that would be used as that's where it would search first as I even tested it on the BS by first uninstalling the Superuser update from Play Store so it would update the binary which in this case is actually downgrade and it only touched the one in /system/bin, ofcourse when I deleted the /system/bin but the /system/xbin remained untouched. If I deleted the /system/bin/su, it would update the /system/xbin/su. I mean the thing is I know you talked about symlinked which isn't as dangerous as you really have one version of the su binary in reality but remember the original directions said to put the su binary in two places, you could run into a problem if you are using a different root or if you updated the su and it's talking to the su binary it did not update. To be honest, I never knew there was a reason behind where the su binary resides only that on rooted stock roms, as far as Motorola is concerned, it's always in /system/xbin and it seems like it can be in any of the *bin directories under system as long as it works. The Superuser update on Google Play doesn't seem to work which was why I couldn't get the su working from terminal but after uninstalling the Superuser update, updating the binary that the Superuser apk in /system writes, everything is fine again. So in reality, I wasn't asking about the symlink but rather the 2 su binaries since a symlink doesn't really take up space and you are dealing with only one su binary file and version while putting the su binary in 2 places seems more risky as the two su binaries will not be in sync when you update using the root tool. The scripts and other ROM developers may have had the su in /system/bin because the devices they learned from had it placed there and then everyone learned from the same source but it doesn't mean it's correct. Google/Motorola/Verizon which were the three companies that push the first iPhone challenger seems to have su in /system/xbin and the Motorola Droid 1 I have still runs froyo 2.2.x which never had a problem with any tools that require su access.

As far as your comparison, WinAmp is available for Linux and even when WinAmp originally came out, you can't call Windows a OS because Winodws was nothing more than a shell that required running on top of DOS as far as the consumer side of things went as it wasn't until Windows XP when the NT side and the consumer side of Windows merged that didn't require DOS underneath. Your comparison is still not the same since basically Windows even as a OS includes the things that it comes with and all the stuff in it come from Microsoft, then whatever you install would be called Windows applications. The same is true with Mac OS, FreeBSD, NetBSD as taking the last three, all the stuff in /bin, /sbin, /usr/bin, /usr/sbin came from the same development. Linux on the other hand is different because Linux is just the kernel, the stuff in /bin, /sbin, /usr/bin and /usr/sbin is packaged by others and distributed as distributions and that is a fact, you can even research this. What you call a Windows app or a app in Linux, OSX, BSD would be what's in the /usr/local folder anyways as those are apps added by the user. When I said userland, I was not referring to user installed apps but rather what comes when you install the OS as part of the included tools which are usually maintained by the authors of the distribution but with Linux, there are over 600 distributions and it's whatever each distribution wants to include in that distribution so saying you are running Linux really means nothing because it depends on which distribution you are running instead of a standard distribution where everything inside the package is alike between computers. WinAmp is still just one product and no matter where you get WinAmp, it'll be the same, you will not find a x amount of different WinAmps using the same version number.