Bit of a technicality this one as your right when you say cleared atltitude on sid is 6000 (with two stop offs). From a controllers point of view as these are effectively stops rather than "pass not below" we like to hear 4000 as your climbing altitude because the climb to 5 and 6 is a few miles away. This is due to interaction with LL outbound crossing over you who go directty to 6000 so you can understand why we panic when you say climbing 6000.
As I say a bit of a technicality but in short, report climbung to 4
Hope this helps.
TT