I have no practical experience of Win 8.1 so cannot offer an opinion on it but have seen a number of threads where those users have also had connectivity problems.
If you already have an 8.1 disk, why do you need to purchase ?
If you do decide to go ahead with its install, first run the 8.1 Upgrade Assistant
http://windows.microsoft.com/en-gb/windows-8/upgrade-assistant-download-online-faq to check for compatibility issues and create a full system image before installing should you need to fall back.
I'm not sure how long it will be before Win 10's release and there are rumours that the Enterprise version will be offered free - with purchasable apps.
As MS are trying to put as much distance between themselves and Win 8, it's not known how long they will continue to support 8.1.