I'm converting an .avi to a .flv and am looking to third parties for encoding.
The Flash 8 Video Encoder does not provide enough options to create a high
quality .flv. So far I've tried Flix Pro, Swish, Turbine, Riva, Allock and
Sorenson Squeeze. I have found that Sorenson Squeeze seems to provide the best
output.

What I'm really looking for is anyone who has experience with Sorenson Squeeze
or anyother encoder and can provide input on why or why not this would be a
good option for converting an .avi to a .flv. Any input or suggestions would
be greatly appreciated!!!

try ffmpeg:
- open source(free ...)
- add flv meta data so you can use onMetaData event in your swf
- can be automated on a web server
- do a very good job(quality, speed)

-- download
http://ffdshow.faireal.net/mirror/ffmpeg/

-- doc
http://ffmpeg.mplayerhq.hu/ffmpeg-doc.html