We went for 8 years straight, 2002-2009. Saw them the first time at the Detroit Opera House, once in Grand Rapids, the rest at the Palace.
*disclaimer* this is all based on the East touring group
Great show, but....part of what we loved was the Christmas/hard rock/talented music mix. It had laser, lights, fire rock and roll...and you walked out in that "Christmas mood". They used to do a lot more of their Christmas music in the 2nd half, had MANY more slower songs with excellent singers. Between Daryl Pediford passing away and Jennifer Cella leaving after her child, they have struggled to find good enough singers to match them and the set list seems to be migrating to an extended instrumental rock jam. They started pushing some of the Night Castle stuff before its release (including opening the show with it, ugh).
Still amazing, I have checked out some of the stage rigs the last couple years, but in many ways that interests me more than the show itself now.
In the end though, I agree with the OP. You should see them AT LEAST once Great show, take my jaded ramblings with a grain of salt.