The down side to using a spindle sander for pattern sanding is ….. the spindle… the smaller diameter like 1.5” heat up too fast and you are constantly cleaning them, or replacing the spindle… even the 3” spindle will eat sanding sleeves…..your best bet is an edge sander with a longer belt.
I have a nice spindle sander, but only use it for shaping riser grips.
I don’t think you would want an occellating sander for patterns either. There are a number of cheap robo sanders and others you can use in a drill press, but you won’t be happy with them at all…