Differences in Walther GSPs?

I've been looking at some of the Walther GSPs available for sale online and noticed that some of the top sections have a slight slope leading to the rear sight while others are flat.  Are the sloped models the newer versions?  Is this a good choice for .32 caliber?  What versions should I avoid?

Avoid the older silver trigger model that comes up from the bottom of the trigger guard. They have horrible triggers. Later versions with adjustable black plastic triggers are much better. 
Jon

Jon Eulette wrote:Avoid the older silver trigger model that comes up from the bottom of the trigger guard. They have horrible triggers. Later versions with adjustable black plastic triggers are much better. 
Jon

Is this the one (single stage) that you're talking about?  If so, it accounts for most if not all of the ones I've seen for sale.
http://www.carlwalther.com/single_stage.htm

Yes. Pass on them.  The are also priced way too high. I've shot close to 50,000 rds through .32 GSP and there's a huge difference. 
Jon

You can swap the two-stage trigger for the single-stage. At least on some.

I wouldn't call the single-stage horrible, but the two-stage is definitely better.