The problem with plate chillers is keeping them clean. Unless you can do a hot caustic CIP, you will never get it as clean as you think.
This is exactly the reason I switched to a convoluted counterflow chiller. The plate chiller definitely cooled faster, but I typically felt like I had to disconnect my plate chiller and put it through about 30-40 minutes of the oven clean cycle to make sure all of the residue was vaporized.
With the CCC, I just run the recirculation loop with some hot PBW and it cleans that sucker very well in place.
I was chilling in about 8-10 minutes with the plate chiller, and now I'm at about 14 with the CCC using just the straight groundwater from the hose. With the hassle factor of the plate chiller, and I'm fine with waiting an additional 6-8 minutes.
The convenience is definitely the selling point of the immersion chillers as well. If you do go that route, just go ahead and spring for the 50' chiller over the standard 25', or else you'll find yourself wanting to upgrade pretty quickly! Well worth the extra $30-40.