I use normal scissors to trim heels for my Dexters. The edges may not be perfectly smooth after hacking it with scissors, but it is safer than having the heel stick out too far from the edges and possibly catch on something.
If I recall, the replacement heels and soles are designed to fit up to a size 15 shoe. So anyone wearing less than a 15 will need to do some trimming to get them to sit flush with the edge of their shoes. When Dexter uses the term "fit", I believe they are using that to mean "will attach to", not necessarily be perfectly aligned to the edges without trimming.
Don't expect to get 10 years out of the "9"'s. A family member bought a pair, and the bottom of the shoe started cracking after less than 2 years. Emailed Dexter, and they freely told me that the "9"'s are not designed to be durable. They are designed for comfort and performance, but not durability. They wouldn't cover them under any kind of warranty as they deemed the cracking/splitting on the bottom to be normal wear and tear.
