Sony A58

Sure, the body is made of plastic, but processed very clean. Are there any arguments against plastic? This is suggested, that the body is lighter. Because the Sigma lenses, I prefer to weigh properly what. To put it bluntly: I'm interested in a camera so only the software and the sensor. After all the components are there which are important to the used lens, the picture quality!
Wifi wireless GPS and all the other - allegedly promotional - "must have frills" does not interest me, because the only cost anything unnecessarily. Snapshots to send I do with my Sony Z1 Experia phone, because I've always man.
At the moment, I compare the picture quality with my Sigma 17-50mm F2.8 lens at both alphas that I own. On the A58 and with my A65, which is of course more expensive. I can see no discernible difference even with kritischstem visual comparison. Laboratory values ​​do not interest me the bean. For me, it's what I see! What I'm going to keep well?