> at UltraDMA mode 5 (which is ATA100).
> 
> Do the drives actually operate at Mode 5 or is it a
> lesser mode (such as in other OS's like Li**x)?

yes they do. 

> Are there any *reliable* benchmarking tools to check
> performance of disks too?

dd if=/dev/rwd0d of=/dev/null ns=64k count=8192


> 
> I'm currently investigating these as alternatives
> to SCSI disks as they are half the cost and they
> are almost as fast.

half?!  1/4 costs!!!!

if you do not need to connect 20 drives to one machine and place every HDD
on separate channel it's performance is comparable to scsi drives.

 
> BTW - I'm running unpatched NetBSD 1.5 as provided
> on the CD set.
> 
> Any help appreciated,
> 
> - Chris.
> 
>