Got a quote today for a Trane 4 ton (replacing a 3.5 ton) XL15 outside
unit with a matching Trane coil inside. Installed was $7800. I'm
thinking a more fair price is $7000 but this is just based on some
brief internet reading.

I was told that a 1/2 ton upsize is not a big deal. In general do you
agree? I'm guessing the a/c guy who spoke with me is correct.

I'm going to get another 1 or 2 bids but meanwhile any suggestions or
comments? Thanks.