Was hoping others would reply to this..... I know there are a few others who use Saxon here.
My 7 year old son is almost finished 7/6. Plan is to finish by the end of the year. We did 5/4 and 6/7 quite quickly but then we got about 1/2 way through 7/6 and pretty much dropped it for close to a year as my son was sick and it was just too much of a struggle to get him to do math or much of anything else until he was feeling better.
We never did the earlier years. All we did was a (American) kindergarten workbook that I had and than a (Australian) grade 2 and I think part of grade 3 workbooks that again were simply because I had them. Then we jumped into 5/4.
From memory I think he was a bit over 5 1/2 years old.
We chose Saxon because it was a solid program that was well recommended among homeschoolers and if we follow it through I know that he will be very solid in math. It was also relatively easy to get second hand copies of including solutions booklets which become important the higher you go.
I think I'm using the older editions but would have to double check. I know they are
recommended particularly as you get higher.
We don't do the supplemental booklets. The drill sheets are beneficial but they are long for young children. For basic multiplication/division I think an ipad app would be easier and a lot more fun.
We just read the lesson together from the book.
We don't tweak it or keep it fun
Which brings us to where we are at this point. It has been good but it is definitely not fun or inspiring a love of math in my child. We will definitely finish 7/6 but I'm not sure where we are going from there.
I also have a 4 year old daughter and I'm not sure whether I will use Saxon with her or not. She is just a different child and doesn't seem to pick up math ideas as quickly as my son did. But I will see where she is in a year.