Interesting article. We are using Paymill and it's very easy to use (official extensions for Magento and other eCommerce systems). Our old payment provider was a pain to work with (uploading excel tables to process the payments...).
Does the official extension do everything you require? We have actually just released a magento extension for Stripe and were looking at porting it over to Paymill but after some research figured out they had an official open source once so we are trying to determine if it's still going to be worth the time investment.
Yes, we are just running a small store though so I don't really have a lot of special requirements.