I happened across this forum somewhat by accident, but I have to say that Uwe Luserke is a thief. He sold a number of my stories to foreign markets, without telling me. I only found out about these publications via the web. In every case in which I contacted the publisher, their attitude was that the problem was mine, since they had paid Luserke. It is difficult for me to understand how a publisher could not be aware that Luserke is a thief, but perhaps in their shoes I might take the same attitude.
Whether or not you engage him as an agent, nothing prevents him from simply stealing your work. In my case, he contacted me after I'd sold a few short stories and asked if he could be my foreign agent. He even sold a couple of stories and sent me checks. However, when Richard Curtis became my agent, the deal was that Richard would also handle foreign rights to my novels. I told Uwe this, and he was quite upset. Thereafter, I had no contact with him, but he apparently continued to represent himself as my agent, and kept all the money.
It's a sad story, but I tell it in hopes that no one else will have anything to do with the guy. Bear in mind that it isn't just the small amount of money involved that is so irritating. He also robbed me of the knowledge that I had folks in other countries who were willing to publish my work.