Phil:
One option may be from a company called Transmode (http://www.transmode.com/). They have a âpizza boxâ platform (TM-101) that will accept a one-channel 10Gbps transponder or two channel 'liteâ transponder. The two channel lite transponder uses pluggable 10G XFP interfaces. The solution is designed for DWDM, but they may have qualified a lower cost, gray 1550nm XFP that would be suitable for your application.
I do not know anything about the products performance or pricing. It may be the 15454E solution would be less expensive if you consider new product learning curve (if you are using the 15454E today), network management, spares, etc.
Good luck.
Tom