The plastic on the 7900 is fine, the plastic on my 361 is in no way better. The carb to cylinder mount is similar to husky's setup, and I personally like it better than Stihls setup. The throttle cable is also fine, I actually prefer it.
The early chain adjusters were weak, and they would easily break. The newer ones won't brake, but they're not as smooth or as easy to use as Stihls.
The filter could be better, but I haven't had any clogging issues. It does however let in some fine dust, but then again so does the filter on my 361.
I think the 7900 is a good strong saw that will last most people a lifetime.
Andy.