WO FF IV gets my vote absolutely. My latest image here:
http://www.iceinspace.com.au/forum/s...ad.php?t=59695
Check out the 1600px version.
I haven't tried the WO FF II, but understand it gets good results too. It's also a 0.8x reducer. The IV isn't a reducer, in fact it's around 1.1x.
I did try the FF III on my ED80. Not good.
That ED80 0.8x flattener looks promising.