I've migrated from the Pany G1 to the NEX-5, and I'm very happy with the results, especially for narrow DOF shooting
Here are some of the lenses I have collected from the FD mount; I will soon add some sample shots from each lens to show their performance.
The Canon FD 24mm F1.4, which I find handy for available-light work. There quite a bit of CA on the edges, even on a 1.5 crop. Although the are reports of the FD 24/2.0 being sharper on the 'net, I have owned both, and I sold the F2.0 as this is better in all respects.
55mm F1.2 Aspherical. This lens is pretty good; not quite as sharp as the standard 55/1.2, but it cuts out the spherical abberations.
The FD 85mm F1.2 Chrome breech is awesome! Super sharp wide open, and the 9-bladed aperture yields a better bokeh than the modern EF version. One of my favorite lenses!
Demo shots coming soon!