Just to add a bit of weight to the request.
We have a similar requirement for a 100Mb FE SFP interface.
We use the C5K175-24 switch as a distribution switch at some of our campuses/depots to connect various buildings via fibre SFP.
The problem is that we use XSR-18xx series routers (X.21 Interfaces being a requirement at certain sites and QoS on XSR is much easier to configure in any case than on a C5).
Also, the XSR-1800 series only has two 100Mbps FE ports.
The above C5K only supports 1Gbps (via SFP).
Yes, we could ad an (Entersys) MGBIC-02 to the switch, but that only operates at 1Gbps.
Our work-around thus far is to install an additional 24 Port A4H switch and use tagged ports then to get the various vlans via a 100Mbps port to the XSR router.
I was hoping the MGBIC-100BT would work, but that does not appear to be compatible with C5 series (according to the Tranceiver Data Sheet of July 2013).
I was also investigating the "Extreme 10/100/1000BASE-T, SFP, Hi" module (Part Number: 10070H) but cannot determine if it would be compatible with C5K devices.
So I will be watching this with interest.
Eugene van Heerden
City of Cape Town