The ST1000 is a bit slower and has a different, weaker, drive than its big brother, the ST2000. The ST1000 spec says it will handle boats up to 6,600 lbs. The O'day 25 is something like 4,800 lbs so the ST1000 is in spec for the boat.
Still, when I had my O'day 25 I bought the ST2000. It has a better drive in it, faster side to side movement and is designed for boats up to 10,000 lbs. After researching in the forums I felt the ST2000 sounded a bit more robust.
A search in these forums for the ST1000 and the ST2000 should give you an idea of whats preferred.