I do love the simplicity of the component Oli.
I know you've said that potentially allowing credit card payment through paypal is possible but would make the component not so simple. I do understand... I feel this function would complete the component though, at least for my needs. I have many customers that have lost interest in downloads when having extra steps (such as signing up for a paypal account) in the process.
I feel with this option it would be worth that much more if order completions go up due to it's availability.
Again, I know it's not the easiest nor simplest to apply but I would be very interested in giving a proper refund
for your efforts.
If it's too much of a reach, no big deal either.