Thanks, Whitey! You are right, we cannot advise anyone to remove the blade guard for safety and liability reasons.
We have found that if you run your robot only when the lawn is dry, there is no grass buildup under the blade guard.
Another advantage of keeping the blade guard on is the blade will no longer get caught under the metal plate on the underside (Professional, Evolution, LB3210 and similar models). This also won't happen if you lower it a bit as well.
Also, as a general guideline, people who choose not to follow our advice and keep the blade guard on should please save your original blade guard and put it back on before sending your robot in for service. We are required to include it so if it comes to us with no blade guard, you could get charged up to $50 for the replacement.
Robotlady