I think, the reason why the German system is so difficult to beat is, because it is based around the need to register your residence every time you move.
Voting for homeless people therefore is a problem.
I also think, that that would be the main reason, why it would run into difficulties in other countries (or states), that do not have these strict laws - do not have the unified system.
The other thing about the US and please correct me if I am wrong. Very often you do have not just one vote, but there are a lot of things to vote for at the same time. (Majoral, jey - or ney to gay marriage etc.) I always took that as the main reason for having a computerized vote, not just ahving to count one vote, but many votes at the same time. Is that correct? I cannot remember having more than two issues to vote for on one single voting day - that certainly made it easier.

The other thing, For me technology is always the slave and never a necessity. If something can be done without technology, simplify. Never use technology for technologies sake. but that is just me.