In my opinion, the Star wheel dresser is best used to unclog a wheel that has ...... been clogged
A single point diamond will serve you well if you are careful not to grind the diamond mount. A wheel that gets a little out of balance due to heavy use can be restored to true running because the diamond will cut it. Use a tool rest to support the diamond. It cuts the stone easily, so you can afford to take light cuts, rolling it as you use it to keep the diamond wearing evenly.
If you want more accurate dressing, then rig up a swinging holder to sweep the diamond across the wheel, or use a natural axis of the machine to move the diamond to dress the wheel perfectly.