i can comment that locking the flites makes them handle more rigid, and in my opinion, much better. highly recommended. i did it to my 10 and 12, and they handle a lot more like the newer flites( i have an 8 ), which only have 2 pulleys.
i locked them in the way shown in the pic earlier in this thread, however, this does put load directly across the pulley eyelet. i suppose this is not a problem?