I don't have time to read this thread, so I don't know what you all have been saying. (But Cuttenwolf filled me in a little one day, so I've been wanting to post my opinion.)
Topping is topping and it's wrong no matter the specie, period.
In general: You can take a bradford pear or variety of callery pear and trim it to establish a good structure when it's about 8 feet tall.
Then over the years, every 5 or so, thin it out and maintain good structure with good strong u-shaped crotches.
You will then have the longest lived healthy callery pear, that will always looks like a tree, not a hat-rack. It will need minumum maintance over the years.
Topping is a short solution, that will shorten the tree life. Once topped, the tree is basically ruined.
Topping is wrong. If your doing the same thing, but calling it something else like "hard-cut" or the incorrect term "pollarding" it's still wrong, you are just searching for a word that doesn't have such a bad name.
It doesn't matter the specie, it's wrong!
Make an exception for one specie and there's bound to be more added to the list.
STOP TOPPING!
We will be the first tree service in the yellow pages book in our area to state in our advertisement that, "WE WILL NOT TOP YOUR TREE, TOPPING IS WRONG".