Bugdry,
The bearing on a router bit doesn't care what it runs against, as the outside race is for all intents and purposes 'stationary' compared to the inside race. If the bearing is well lubed and in good shape no issue running it against steel.
The only concern I would have using a steel template is that you could accidentally contact the cutter. I have nicked my wood and plastic templates by accident, and the cutter is spared. Templates can be fixed by bondo or other means, you run a carbide cutter into a steel template by accident and you are buying a new cutter.
That being said, if you used guide bushings against a steel template, there would be no issue. The guide bushing usually allows more clearance away from the bit than a bearing guided bit, therefore less chance of the bit contacting the template. (note I said LESS chance, not NO chance....)
The bearing on a router bit doesn't care what it runs against, as the outside race is for all intents and purposes 'stationary' compared to the inside race. If the bearing is well lubed and in good shape no issue running it against steel.
The only concern I would have using a steel template is that you could accidentally contact the cutter. I have nicked my wood and plastic templates by accident, and the cutter is spared. Templates can be fixed by bondo or other means, you run a carbide cutter into a steel template by accident and you are buying a new cutter.
That being said, if you used guide bushings against a steel template, there would be no issue. The guide bushing usually allows more clearance away from the bit than a bearing guided bit, therefore less chance of the bit contacting the template. (note I said LESS chance, not NO chance....)