We are connecting a 5170 to a 8700 using (2) Tunable 10G SFP+'s (XCVR-T80W01) through a 4 channel DWDM filter (CN-100-E4L) for a total of 20G point-to-point. In the (009-2011-602)_Transceivers_Reference) Revision T, it says the XCVR-T80W01 and XCVR-T80W02 are not currently supported. However, when you do "port xcvr show supported" on the 5170, it says the XCVR-T80W01 is supported.
However, when we tried to tune the XCVR-T80W01, we had mixed success. Some of the optics tuned correctly, and some said they were tuned correctly, but would not pass through the DWDM filter. We originally had SAOS 184.108.40.206 loaded on the 5170 (original version). After upgrading to the newest software rev (SAOS 220.127.116.11), all of the optics tuned correctly and passed through the DWDM filter.
So if you have a 5170 and are using tunable 10G SFP+'s, and are having issues tuning the optics, check your software rev on your 5170 and make sure it is up to the most recent rev.