Don't have a document for you but i can share my experience when deciding what to buy about 6 months ago.
We were looking at cisco, foundry, and extreme. Our config was the cat 6509 vs FastIron1500. I liked some of the features in the Fast Iron (such as sflow, similar cli, quick support). But the one thing that i needed was gigabit port density. (with the lowest subscription ratio). I needed at least 200 GigE plus 16 fiber links and we couldn't get that with just 1 FastIron1500. The other thing i was looking for was full support for 802.1x (they only had support for md-5, not peap or TTLS).
I really wanted the sflow capability (available on all their FI lines) which gives you sniffer like visibilty built-in on every port. Similar to netflow, but netflow is only supported on Full layer 3 chassis based switches.
Overall I felt that the performance was similar between the two. I've read that the FI are slightly faster under full load than the cisco's.
Ended up buying cisco and haven't regretted it ever since. =)
