Problem is that you have two different surfaces on the two balls - and two different layouts.
Thus, we're not really comparing urethane to reactive, we're (this time) comparing 500 vs. 500/4000
I'm not sure which delivery I was comparing - the one I looked at seemed to be at least a board outside - and not just at one POINT, but rather at delivery and then continuing.
Again, I was just using these two videos as extreme examples
to illustrate the difference in how a reactive and a urethane read the lane.
Urethane hooks early and rolls long and reactive hooks late and rolls short and sudden.
By increasing the grit on urethane the skid phase can be lengthened but it will always hook early and roll longer than reactive.
You can see that here in this video on the same lanes after I took my Karma up to 2000 grit.
Now the ball gets more length but still rolls pretty early.
Towards the end of the video you will see the oil guy start to oil the lane.
Now look at how long the Karma goes on the fresh after he oiled it.
It is more like a reactive ball, being very long and late, but without the sudden back end reaction that reactive provides.https://www.youtube.com/watch?v=T40TnHpvzbQ