Saves a ton of weight, too, esp with a leather saddle. I just dont have the oomph anymore–back in my late 30s early 40s I could swing a 45 lb roping saddle up on a horse no problem. Nowadays I think one of my arms would fall off if I tried.
Depending on how wide the slot is on your western tree, you might feel like you end up with too much front to back wiggle room for those leathers. Then again, that wiggle room could add to comfort. The english stirrups could look pretty odd but endurance stirrups wont, and of course they come with narrow necks, or you can cut down the bolts on the metal ones and squeeze 'em down to fit better on narrow leathers.