Less than a week ago I had both of the horns you are referring to. I would say get the Keilwerth if you can spend the money. The 52 is a great buy in a saxophone (I have one for sale). The difference I found was the yamaha was brighter, I play metal mouthpieces on my Keilwerth horns. Keilwerths have a much darker tone than the yamahas, and in my opinion they need to be brightened up a bit. They were both great playing instruments, but the key action on the keilwerth was a little better to me personally. The yamahas are about half the price of the keilwerth, but the Keilwerths have more features. What are you planning to play on the horn?