I have a Model Subwoofer with the Model Two table radio. Honestly, I find the subwoofer to not really be necessary. The sound quality of the Model Two is quite good on its own.
The subwoofer certainly doesn't do any harm. As with all the Tivoli products I've used, the sound performance is just about right. But it's a subtle change from the already good Model Two.
As an added note, my subwoofer's standby feature stopped working unless I keep the level at the maximum. I therefore generally leave the sub off unless I have a particular desire for the little bit extra, and then I turn it on manually. Most of the time I don't miss it if it's not on.