I don't know. That's something that depends on your system configuration. You could try... What kind of shell are you using? kshell,Bshell? you could search for it on your system (usually in /bin, /sbin or /usr/bin), and copy it to /usr/bin/sh.
If you were using this shell, then it'll be ok. If it's a different shell, it isn't a very bad problem, and you'll know when your users tell you that something is wrong ;-) As far as I know the main problem with it could be the scripts.
If users' profiles are running well, then my guess is that your using the correct sh.