I have a Firefly Mini which
jrandeckI have a Firefly Mini which is what it sounds like you have (the regular Firefly is not exactly dinky.) It works pretty well as is for Media Center, though the buttons might not all match up. I haven’t used mine with Media Center for a while so I don’t remember specifics, but it seemed to work fine for basic control.
I haven’t tried using its receiver with a Harmony. I just got a Harmony, though, so I’ll have to give that a try and see how it works.
The remote I use most is a Gyration remote. Unfortunately they’re discontinued but you can still find them if you hunt. It has universal remote capabilities (and can learn codes from another remote) but doesn’t have a lot of the automatic features you get from a Harmony or some other universal remotes. The Gyration also doubles as a mouse, though, which is very handy, especially if you’re not in Media Center all the time. I don’t mind having to push extra buttons to control the receiver or TV when it means having the convenience of having a mouse always there.
BTW, the regular Firefly is an RF remote, so a Harmony won’t work with it. I don’t think there are RF universal remotes that would work with the Firefly receiver. I have the same issue with the Gyration since it’s PC control is RF.