Cisco OSMs for 65XX

I'm looking into an edge 65XX solution for a new DC with multiple sonet connections to GigE and I was hoping for some real world feedback. Particularly, we're considering the OSM-4OC3-POS-SI+ and the OSM-2OC12-POS-SI+. While performance and redundancy may best be served by GSRs with engine3/4 linecards or the big J, I'm not convinced the expense is worth the additional costs. Any hands-on experiences or 3rd party performance statistics are most welcome. Thank you, jeff