The thing is that I don't want to have to look up the password every single post when I know it's an often used password, just not which one.
I personally have no problem with WinRAR checking all the files first before it rejects it, I download on an SSD and it's fast enough and wear and tear is certainly no issue then. It's a far greater wear and tear on my nerves to have to enter the password after having looked it up and seeing it's the same password again as before. It's also a colossal waste of my time in this age of automation.
Add to that that I almost always download overnight and waiting for WinRAR to read it all a dozen times if it has to is really a non issue.
Perhaps could you make it a switch then? Let the end user decide if he wants to automate the password process as much as possible or if he wants to stay hands on all the time. If you'd want to go for gold you could even make UE a little smarter and have it try the password first that was previously successful for that particular poster.
(it would ensure my renewal

)