|You'd have to have him get you a very exact set of conditions. It might be that he could propose a situation that it might seem true. It is true that you can't get the 10/100 to talk to a 1G at 1G speeds so in a round about way it might be true.|
Also some old routers do report wrong. The old router could actually take packets away from faster routers but there aren't too many of them out there.
As for your install, there sometimes is a special port that may be usable to stack switches. Most times any port is fine. If one goes bad another usually works fine. We don't usually replace them for one bad slot.
I am not a bit fan of 1G unless you have some very high end servers. Just don't think there is much true value to anything above 100M speeds on a home computer. Too much chatter taking up processor time.
Set all to 1G and run perfmon on processor then set all to 100M and see if any reduction of processor.
In all not much difference. You can't download faster than your modem
Playing to the angels
Les Paul (1915-2009)