Hello Artaher
Currently have a Technics KN5000 and Yamaha PSR2000 and over the years have had three Yamahas and three Technics. I liked each one for different reasons (voices, styles, operational functions, features).
Didn't get the KN6500 because there didn't seem to be enough differences between the 5 and 65 for the extra dollars, although I heard one and was impressed with it's sound. Both brands have their good and bad qualities and that is based on each individual's likes and dislikes and how the keyboard is going to be used (home use, on the road, training, etc). My personal opinion - I think the Technics is a better built board (assume the extra cost confirms that)- current one I have nearly four years and never had one problem with it. Technics' musical sytles to me are more dynamic although the PSR2000 seems to be a bit improved over previous models. On the other hand the 2000 has a lot of punch for the dollars and has many great features, some of which I wish the Technics had and probably will plus some new ones with next release. As so many others have said, it's an ever changing format and it would be to your advantage to see and try out each brand to see what fits your criteria.
Most of us (I know I do)who are into this arranger keyboard world feel apprehensive about buying a new board because tomorrow something new comes along.
Good Luck and hopefully the one you choose will give you many hours, months, years of musical enjoyment.