Fern,
We are VERY happy with our Chelsee - it does everything we want.
I am a rather large man - weight and weight and height, and one of the seats (with loads of jets) is deep enough for me to relax easily. The back up and service from the company I bought it from have been second to none.
The Optima has a few more jets and a different waterfall with a few more gizmos on the control panel, but I couldn't warrant spending the extra £3k ($6k) it would have cost. There is no way it was THAT much better.........
Sundance is a reputable firm who make a quality product.
You will not be disappointed.
Nosh.