Jonathan, going from 9s to 10s shouldn't be any problem. The clearance over the first fret should be about the same as the clearance over the second fret while fingering the first fret. In other words, check the distance from the top of the first fret to the high E string without touching the high E string. Then press down on the high E at the first fret and check the clearance from the top of the second fret to the string. They should be about the same. If the 10 is too wide for the nut slot (which I STRONGLY doubt is the case), you will see more clearance over the first fret when the E string isn't fretted.
Hope this makes sense.
Bill, tgo