With DSLR you would benefit at the noise level for sure. If you look at the picture no. 2, you can see a lot of noise (as you discovered with a low light situation). It is a beautiful picture, but the noise really takes it away.
A DSLR can help you there, because it has lower noise level at higher ISO. This is when you talk about hand-held images.
Your S2 also has a Manual mode, so try at low ISO setting and put your camera on the tripod, with longer exposure. You'll be impressed.....
Another thing:
If you look at this picture:
In my opinion, the foreground is too sharp. That's the way compact cameras are designed. You cannot adjust DOF by yourself, because it is almost infinite. With a DSLR, you can do this.