I thought about using VPNs but I never really saw the big benefit. Sure, we use them at work to access our internal networks and smokes usage is valid to circumvent regional restrictions but for forum access and downloading, it didn't really seem beneficial. Of course, by the time I started thinking about using them, I also wasn't really DLing anymore.
For forums, you have to log in anyway so who cares if they know your IP or not as they already have knowledge of your email address and possibly the password (depends on how they stored them).
For DLing, it would be effective to obscure your IP in swarms or from the DL site (as long as they VPN provider didn't keep their logs long). I never really looked into them so I don't know if they were packaged like Internet providers, where some are unlimited and others have caps/quotas for speed/throughput. In the day, I would have hit any kind of cap early in the month. Also, VPNs add more hops to your route and your speed is only as good as your slowest hop.
Again, this is just my personal rambling on it and it has been a long time since I thought about it for something like this so might have changed.