To Autodetect or Not

This is sort of a poll on what people think of whether or not to use
autodetect with NICs and switches.

I've been told by several long time networking types that if using 10/100
switches it is best to force the machine's NICs to 100 Full as opposed to
letting the NICs autodetect. I've done this in various installations and
have had issue with this. In some cases the network performance is so bad
it is unusuable. Changing the NICs back to autodetect always cures the
problem. I have also talked to other long time networking types that have
had the same performance issues and have since adopted the policy of letting
the NIC autodetect and not messing with it.

Any thoughts?

Jeffery Rehm