Scott,
I believe the best accountability system utilizes a radio, good officers and a heads-up Incident commander.
When I was in Toledo, we eliminated all tags and rings and went to a two tier system. At first alarm fires, officers arerequired to tell the Incident Commander of where he will be operating before he goes in. If he changes that location, then he must inform Command.
NFPA 1500 and 1561 have sections on Accountability systems. Both use two words throughout that section. "Location and Function". They say the IC must bew aware of every crews Location and Function. They go on to say that each officer must constantly keep Command aware of his Location and Function. Not only that they are in the building but where they are in the building.
All it takes is discipline and radios. No rings, tags, boards or anything.
At second alarms, Command has someone that writes the Location and Function of all crews on paper or a dry-erase board but the same words apply.
If your system doesn't have the ability to track those little words "Location and Function", then you are not meeting the demands of the system and have to potential of big problems.

Scott, Regarding accountability.

We have been trying a new system that is called ICx. It is a digital command board which tracks firefighters throughout assignments. It is used with fireroster.com (a free scheduling and rostering program) which updates persons riding positions to the tactical command board of ICx. There is a youtube video on this product and it can be trial downloaded at batt3.com.

This product does not take the place of feedback from personnel in assignments, or does it take the responsibility away from everyone on the fireground to have a heads up approach to accountability and safety.

It's merely a tool for an incident commander to use to assist with accountability.  

John.

Please let me know how your new system is working.