The shopsmith sled can be used to cut smaller parts but you have to plan ahead and make some adjustments to how you do it as it is in incorporated into the design as it comes from shopsmith. You are also limited to what angles are native to the sled. Yes there are work a rounds for that too but again not from the factory.
The express sled takes a shopsmith miter gauge or the Incra V120 that shopsmith sells and you are not limited by those gauges. I have the top of the line Incra miter gauge mounted on mine. You can set it to .1 degree increments........
The express is also designed to take different hold downs, Incra sells some or you can get them from different sources or make your own. That makes it easier to work with small pieces.
The other option is shown in this thread:viewtopic.php?f=6&t=485&p=3789&hilit=sled+of+sorts#p3789
It is an almost free solution to small parts using scrap wood to make and once worn out it easy to make a new one, and of course you can change things around to fit your needs.