I realize that this is a late reply, but my experience might be useful to someone. I built a very small N layout using the Kato #4 turnouts to save space. It's been a mixed blessing.

I didn't dare pull out the rails and file in notches when I was laying track, for fear of damaging them. Now that they're all ballasted in place on a foam base, there's no way that I'm pulling them out to make this change.

With the wisdom of hindsight, I should have done it before they were placed on the layout. I'm running two Kato diesels that have no problems with these turnouts, an Atlas diesel that is sometimes problematic, and an old Bachman 2-8-0 steam engine with aftermarket DCC that runs very well except that the light pilot wheels constantly derail on these turnouts, and shut down the DCC. Notching the rails would probably have prevented this.

I'm looking for a solution to this that doesn't involve pulling up track. In the meantime, my small expansion will use only #6 turnouts.