Displacement means very little to me,,,,now ergos, suspension etc does. I'd say the K5 is somewhat primitive in that department comaped to my 05 CRF 450 R.
You take a open class monster man bike to a little supercross style track and ask how it will fair?
Not to well for you when you "blip" your throttle on the face of a table. Not advised.......
Take the 500 out where it can run and see how the baby 450 will handle it. Riding a Five o on a small track is like racing a big block in a parking lot.