I use a FS-4HD 40 gig on my JVC 100U. It is not recommended in the Focus compatibility sheet but it works fine (I do not get a view finder status like the recommended DR-HD100). Once turned on it starts and stop with or without tape and I record in MT2 format.

I want to move up to the FS-5 or the FS-H200 due the compact size and removable media on the FS-H200.

Will it work the same on my camera JVC 100U as the the FS-4HD?

I know it's not on the recommended camera compatibly sheet.

I just called Focus Enhancements and the FS-5 and the new FS-H200 will work on my JVC HD100U the same as the FS4-HD unit did. There will not be any status readings in the viewfinder but the unit will start and stop with the camera record functions.

I will soon be upgrading to the new FS-H200.

I've contemplating this same upgrade. I have the DR-HD100 with my JVC HD100 and don't mind missing the viewfinder updates. Honestly, I never use it anyway. I always check the firestore to make sure it's been triggered.