HDMI to RF, some thoughts

[judge]

Sooner or later I’m going to have to move to converting HDMI to RF for my vintage TVs and I am wondering if anyone has any experience of this. There are converter boxes readily available, but I would like something with these features:

1. I should be able to display 4:3 programs on my old TV full height without the bands I would see on my widescreen TV
2. I should be able to choose between letterboxing and other modes for widescreen programs
3. The downsampling should be of decent quality
4. I should be able to watch copy protected sources without artifacts on my old TVs
5. It would be nice if the converter would accept composite input too, so I don't have to have multiple converters
6. It would be nice if I could broadcast the signal, like I can with my old Blonder-Tongue

Anyone know if any of the converters can do these thing? The first four are the most important.