To be honest that's a ridiculous amount of functions to disable, do you even know what each function does? on that note, you've just added aload for it to disable but the major ones have been left out..

My general list to disable:
disable_functions = "system, show_source, passthru, dl, symlink, exec, shell_exec, allow_url_fopen, popen, pclose, proc_open, proc_close, ini_set, ini_restore"
This wont disable a phpshell but would still keep a server secure as it can be by just disabling functions.. if you know your way around php/other functions related you can disable pretty much anything you want from running IE a php shell.