My child also goes to Northshore (first grade)because the public schools in our area are poor and I never have a problem with her being bored. She is one of the top students in her class, reading on a third grade level. You can always ask for support from the teacher to start with and if that fails go to Mrs. Walla, VP. If he's bored in reading, ask to be a part of the accelerated reader program. In Kindergarden, the homework was a little too easy, so she would occasionally get extra papers to do. Also, they were put in reading groups with other kids closer to their own level, but I think that was the second half of the year. This let the accelerated kids really take off with reading.
As far as comparing to Everett and Mukilteo, I really don't know. I know Mukilteo schools are good, and Everett is more hit and miss. If you are dissatisfied, I would certainly display your concerns. I found that they are always open to meeting with parents.