Not an instructor.
Have had the Balance Rite mid cue extension on for about 3 years and like it.
I'm 6'1" and like the idea that now my cue is almost 4" longer (62").
The Balance Rite will add 2oz of weight to the middle of the cue and will change the balance point on the cue.
I had to take mine to a cue builder to have it trued(refaced).
Like Randy has said they are great on 9' tables.