I didn't test if this applies to every wcx plugin, but when extracting iso using http://www.totalcmd.net/plugring/iso64.html SetEndOfFile isn't used so this leads to fragmented files. Extracting from zip/rar/7z is ok. I checked with Process Monitor to be sure. Using TC 8.51a x64
I wrote earlier that Total7zip doesn't use SetEndOfFile. 7-Zip also doesn't use it Tested them with Process Monitor so I'm sure. You can see it yourself, just create filter to include "Operation is SetEndOfFileInformationFile" and start unpacking.
According to your link there was a request to add ths feature to 7-Zip, so it will be available via Total7zip - that's what I mean. However it is a quite old request... so 7-Zip programmers didn't realize it too.