I'm amazed at what the combo of Optical Flow in Compressor and nearly uncompressed 1080i (via nanoFlash) can achieve.

Here is the raw 1080i nanoFlash clip I posted previously, but this time deinterlaced and turned into 60p and then frame rate conformed to 23.98p for 2.5x 'overcrank' slowmo.

It's actually a full 1080 clip and good h264 compression, but might stutter on some computers.

125 MB, 25 seconds

http://files.me.com/mrbarlowelton/anvenw.mov

I think you're always going to get better slomo with 720/60P rather than de-interlacing.

Steve

Obviously progressive is preferable, but in this case I've been surprised at how good the conversions can look with really clean, full-raster 1080i footage.

Did you notice how well the h264 held up on the shot? That rushing water is hard to compress but because the original shot is artifact-free, the final distribution level encoding can be nearly free of the blockies too.

To be honest, I never look at stuff on the net as it never really shows anything!
I can imagine that good, low compression interlaced stuff can look go de-interlaced, I assume it depends largely on the programme (ie algorythm) used to do it - what did you use?
AFAIK this is how the Sony F355 and the new PDW800 do slomo, de-interlacing in-camera, and it does look good, even with their 50 mb/sec compression.
Steve