In the US it is illegal for a manufacturer to deny warranty to anyone who does not use an authorized dealer for service as long as the service is recorded and or a receipt is available.
As far as the next service I change my oil on my bikes at 2500 miles I assume you mean 6000Km on service interval which would be 3,728 US miles. Using the GS 911 I am able to set whatever miles and date I desire for the next service I simply entered 3,000 miles which left me with just under the 2500 miles I feel is optimum for oil life.
I have found through the years that there is a noticeable difference in the shifting of most bikes once the oil has around 2500 miles on it. Therefore I have accepted the fact that the oil starts to break down at that point and should be changed.
Keep in mind that not only does the oil lubricate the engine but also the transmission and clutch which can generate quite a bit of heat and sheer action on the oil shortening it's lifespan. I would rather do a few extra oil changes during the life of a bike than repair internal engine, transmission and clutch components.