WOT is more than about blocking threats.
In fact I would say that that is its least important use.
ISTM from my experience with WOT is that its main feature is content warning.
Of course there are a gazillion other ways to get content warning but I have found WOT to be one of the best in this area.
My understanding is that WebRep also does some of that which is good.
ISTM that for whatever reason, Avast decided to incorporate WebRep into the avast! products. Personally I think that this was a Marketing decision and a mistake.
ISTM that WebRep should have been designed as a separate Addon to Firefox and IE just like 95% of their Addons. This way someone could just go to the Firefox or IE Addon (Extension) website and install the Addon from there without having to even use avast! Free, Pro or AIS. Just put the avast! logo on it and name it avast! WebRep. This way it could be maintained and updated with Firefox and IE updates and not have to be tied into avast! Free, Pro or AIS and their respective updates. Other AV companies do this on select free products as a marketing tool for the company.
The other advantage of doing it the way that I am suggesting is that I doubt that anyone uses and/or buys avast! because of WebRep. However, if people who don't use avast! Free, Pro or AIS are able to download and install the WebRep directly from the Firefox and IE websites they may more inclined to try avast! if they like the WebRep Addon/Extension.
As to whether Firefox is superior to IE or Google that is a personal choice based on a lot of reasons many of which have nothing to do with technical superiority of one product over another. If others prefer IE over Firefox and Google that is their choice. I happen to prefer Firefox and ISTM that Avast made a bad Marketing decision by incorporating WebRep into the avast! product and not making it a separate Addon/Extension available for download directly from Firefox, Microsoft websites. Of course Avast may be more interested in keeping their Google user customers happy than their Firefox user customers. That is a business decision and if that is what it is then so be it.
As far as the version numbers the version numbers don't mean squat. The version number on Windows 7 is actually 6.1xxxx so version numbers are useless.
However, I can tell you that from having used Firefox going back to version 2.x that version 6.0 is by far the best version in many respects. Version 8.0 x64 takes advantage of x64 architecture for those that have a Windows x64 OS. IMO there is a clear net advantage to users in running x64 products on an x64 OS versus running x32 products on an x64 OS and to running x32 products on an x32 OS.