I have both the Trio and the Trio+.
The main advantage of the Trio+ is that it has a built in looper, so you can record a rhythm track with your guitar to go along with the drum and bass track the Trio+ generates. You can do the same thing with the Trio and a looper pedal, but it's difficult getting your rhythm track and the Trio bass and drum tracks to be in sync. By having the Trio+ do both the drum and bass and the looper, it automatically syncs it up.
The Trio+ also has more modes and flavors of drums and bass.
I can recommend both of them. They Trio was selling for $50 when they released the Trio+. For jamming both will work. But being able to a rhythm guitar track and then the lead also is the main advantage of the Trio+.