My company is currently evaluating both Foundry (netiron line) and Juniper (m160 and t320) devices to use in a high speed l2/l3 core with l2 mpls. Core speeds will start at oc48 (ospf and fully meshed ibgp core, full internet routes, peering, customer routes, etc) but needs to scale to oc192. Dense Gige is also a requirement.
I of course have both companies data and testimonials but thought I would go to some actual network operators to get opinions on one or the other as a preference. I have heard some negative things about one of the above vendors ability to handle a lot of routes in less than stable conditions, bad optics, mpls was also brought into question as an issue.