Of course, your company is just a small part of the total user base for a commercial application. So, you'll have to bear with upgrade delays as you plan the impact of those applications on your single logon system. A number of pressures work against the success of the single logon. For instance, a significant portion of this problem comes from the constant addition of new applications created by authors who have never heard of single logon or who believe they have a better idea. Kerberos offers a low overhead for authentication, but faces major security-breach risks and scaling challenges.
Digital certificates are the mirror image.
They have a very low security risk with excellent scaling, but have a much higher overhead for authentication. A 1993 effort by MIT and Digital to bring the two groups together imploded. Since then, the use of these technologies has grown. Kerberos has b een more successful in reducing the number of logons users need, while certificate-based systems have so far only added to the number of user logons. This situation is starting to change, however, because certificate-based single logon systems are emerging.