At that time the 6100 was usually on backorder with most vendors and perpetually out of stock on our end, it just is very unusual as a result. It is very difficult for me to get warranty coverage from the factory in these instances. German law is written so that the two year warranty is from date of manufacture, the consumer has a two year warranty as well but where the manufacture date and sale date differ the warranty is paid by the reseller. I understand that US law is different but extreme exceptions like this are very difficult for me to argue for coverage on my end. In a case like this in Germany anything that were to happen in the two year warranty period would be the expense of the retailer. The only difference is color indeed but the age of the pump just puts me in a difficult position in terms of proving it is new and should be covered and that the receipt corresponds to this purchase, that was my point.
The newer impeller can be quieter but it depends on the source of the noise. It has fewer parts and reduces the noise of on and off use and intermittent noise issues but some sources of noise can actually be slightly worse. I think the best resolution would be to get the pump in so I can test it and try different parts and basically hand fit parts to reduce the noise.