This is why people either need to be responsible enough to rate limit downloads/uploads or use QoS, a faster connection only masks the problem, it doesn't fix it.
I get where you're coming from, but at the same time if the ISP are providing kit to allow connectivity to services they're being paid to provide, they should ensure that the kit can handle it imo.
The SH2 just can't handle 500mb/80mb from my experience shared amongst devices, the fastest one essentially wins and takes the rest offline, hence the reason for a third party router being needed, but then, you lose digital voice unless you have both devices on. It must be causing them and Openreach a bucket load of unnecessary support.
I understand there is a SH3 in the works, whether they add anything worthwhile into that or not is another matter, it'll probably be the same old feature set with faster wireless, again, masking the problem.
You have to appreciate 90%+ of users of their service won't even know what qos is in most cases.