I get what you are both saying but neither of you have said you have done it based on what I am reading. I've brined the salmon and watched with agonizing pain the hours it took with the pans of smoke.
I've made wooden dowels and hung sausage placed on the top of the Big Chief rack and smoked them using nitrate.
I have placed 2" of R 12 insulation in the bottom of the original Big Chief Box under the burner leaving the smoker in the box to aid in temps. Then set it out in the driveway with a wind break in case it caught fire. I have worked the Big Chief in several different ways. The aluminium pan that catches the oils corrodes pure and simple. It stinks after repeated use and it does not come clean. You can't burn off the odour because the smoker does not get hot enough. They're not the same as a WSM, nowhere near. As other have said burn off any odours. You cannot do that with a Big Chief!
Catch the drippings from fish in a disposable pan or tray and you will not have that problem, pure & simple.
I have not read a single post including anything that Harry Soo has said where he has actually done it and ruined a WSM.
I totally agree that everyone is entitled to an opinion. Some are based on fact, some are not.
I've already stated that I swap back and forth between beef jerky and fish in my Totem frontloader (Big Chief predecessor) and don't notice a difference.
The inherent problem with trying to smoke fish on a WSM burning charcoal is that you cannot hold temps low enough to properly smoke fish.
Now if you want to smoke-roast (read cook) some fish, have at it.
If you want to truly smoke fish on a WSM you will need a smoke generator and the WSM will effectively become a cold-smoker box.
Even the Chief smokers will run too hot on occasion (as in Spring, Summer, Fall).
There are many, many home "fish smokers" that are actually cooking their fish. That percentage goes way up when the "cold smokers" chime in...
The Chief smokers are made within 50 miles of my location and there are a ton of them in service out here.
We smoke A LOT of fish in the PNW. I'll bet more per capita than anywhere in the Lower 48.
Here's what I had to do to mine to get good product...
http://www.ifish.net/board/showthread.php?t=679378&highlight=big+chief+mods
So in summary, with all the odor issues (if any) aside, the WSM is not a good fish smoker candidate unless modified with a smoke generator.
This makes any residual fish odor issues a moot point in my opinion, unless you want to pursue the smoke-roasting of fish or modify the WSM to properly smoke fish.