Hey Will,
I do not have experience using any Foundry boxes.
I do however use Riverstone extensively; my whole network is composed of
RS boxes ranging from RS3000's up to RS8600's.
I have an RS8600 handling my core routing right now! Im taking full bgp
tables from 3 upstreams and several gig and ds-3 links for my OSPF
backbone.
I used to have a 7206VXR trying to do the same.
The cli is in my opinion easier than Cisco's IOS to learn. It has plenty
of neat features that make it very user friendly.
The only issue I have had is with the way it handles flows. I used to
hit 100% cpu utilization when my traffic peaked due to the way the flows
were handled. However, the problem was sort of fixed by enabling
Riverstone's version of Cisco's CFE and move the flows to the ASIC's in
the linecards.
Just as an example during my peak usage I move between 300-350Megs of
traffic and my cpu barely goes above 10% utilization.
The draw back is that I can not use ACL's as effectively in my core, so
I moved all my ACL's to my edge routers!
Oh, and they are a fraction of the cost of the other big name brands.
If you want any more info you are more than welcome to ask.
Regards,