In one word: YES, YES, YES!
My husband and I did this tour a few years ago and we loved it. There's lots of historical information and backstage information, including a trip to the utilidoors tunnels. We have been to WDW several times too, but the trip added something to our visits to the MK by giving back ground information. When we look at things in the parks, we remember why it is like it is. It makes the park more interesting.
Also, if you can get the earliest reservation, you can wander Main St. and get great pictures with hardly anyone in them.
Our CM guide was wonderful and made the trip extra special.
There is a lot of walking, but you do get short rest periods. We had lunch provided at Columbia Harbor HOuse, upstairs, which was delicious. I don't know where they are having lunch now?
I hope you decide to do this as it's a great deal for the price, IMO.