I don't understand where the kidding comes from. The connection is secure and most AVs use stub/smart installers. They also save mb on based on an offline install and always have the up to date definitions from before hand.
Sorry, but it can only be a bad joke if you offer both online and offline installers, but tell me here that online installers do not work correctly. Sorry, but that sounds like a confession of bankruptcy. Btw.: I have here the situation that on many PCs to install the line is very thin, unstable (breaks often after some MB, at some max. amount to download in one piece is less than 10MB), too expensive (both in time and data amount) that online-install is just not practicable. So offline-install is absolutely mandatory – online-install is out of discussion. So the method is to download offline-installers the same day the PC will be installed, and for virus definition updates the line is enough – and that's done immediately after install.
If it is really the case that for each and every program update the whole clean install procedure has to be done, avast would just be unusable and a bad joke.
Hmm ... I'll then better install v4.8 in those cases – that's not running into program update flaws ...