At 9.9kg this case from Roland was the answer to my quest in keeping the weight down to a minimum.
Keyboard players have always had to endure mainly heavy instruments when using weighted key beds. Add the weight of a flight case and you could be looking close to a colossal 40kg.
The Roland SC-G88W3 is well made with 3 handles and wheels, it is also nicely padded with straps to keep the instrument from moving whilst in transit. This case also looks good with the Roland logo and piping plus a large pocket for storage.
If you're going to be with your instrument loading, unloading & setting up etc this is the answer, it will save knocks and so on.
If however you're lucky enough to have roadies then a hard case would be advisable.