Using PS to gain Dynamic Range (3 img)

Following from THIS thread that Owen posted a few days ago, I have been going back over a few photos, using the process described in the previous thread, to obtain better dynamic range, using multiple photos (or the same NEF but processing it twice with a dark and a light version).
The results I achieved are:
1.
2.
3.
I'm not 100% sure if this method actually gives you more dynamic range, or if it just gives the illusion, however it does seem to make quite some difference.
Has anyone else tried this method and what results have you had ?
The results I achieved are:
1.

2.

3.

I'm not 100% sure if this method actually gives you more dynamic range, or if it just gives the illusion, however it does seem to make quite some difference.
Has anyone else tried this method and what results have you had ?