Well, I am not participating to this discussion to solve a personal problem. Actually, I am not going to use geometric algebra. I just want to know if there is a convenction or not. And I thought it was interesting to show that any preference has its pros, because you seemed to be interested in defending a particular preference.  

Do you mean you never look at numbers to understand if your calculations are correct? There exist some people, I guess, who use geometric algebra for practical purposes. People who express measured or estimated physical quantities using multivectors. And if they do, they for sure are going to look at the numbers. Results must be interpreted, discussed, understood. Programs must be tested. Their output cannot be accepted blindly. Then results may be shared, may be sent to other people, or the output of a function may be used as input for another function. And this is why I believe a convention might be useful (see "Relevance").