I got one of the 40 plate chiller from Duda Diesel. That thing is amazing. I have use other type of counterflow chillers and so far this is the best. It took 5.5 gal for wort from +220F down to 63F in less than 4 1/2min (OK for the record, the incoming water was around 45F but I had the valve choked to 1/3 open). I was using my trusty Chillzilla before I got the plate chiller. It did a very good job cooling down the wort but I like the plate chiller form factor. One last fact, I use a hop bag and Bazooka screen in my BK (I heard the plate chiller will not react well to solids and stuff
!). In addition, I have it set up as a gravity feed. No problems run the wort!
I will strongly recommend it. I got my directly from Duda Diesel. Excellent service and lightning fast shipping. Here is the link just in case (did I mention the price, ~$95)
http://www.dudadiesel.com/choose_item.php?id=HX1240
Hope this helps.
Cheers!