I really struggled when I bought my GS350DL. Even with the discount and getting it for under $70 at Radio Shack it didn't take any longer than a day to decide that the build quality was so poor that it wasn't worth keeping. The tuner switch felt so cheap that I swore I would break it in less than a month.
In contrast, I ended up exchanging it for the S450DLX and with the exception of breaking the telescopic antenna I've been pretty happy with it. The only things that bothered me is that one tuner switch felt as cheap as on the 350, and the coaxial power jack is somewhat sloppy. Other than that, I prefer the 450 over the 350.
As an FYI: Eton let me know the replacement antenna for the 450 is the same one used on the 350.