Chris. This would be a great topic for the people who have actual first hand knowledge about tree size/spur type/rootstock used and if they prune and fertilize these trees differently.

My plan would be to grow the tree as fast as possible and not crop the tree until it has reached the size desired. But that might still leave one with a weak tree lacking the vigor needed for the long term. A vigorous rootstock would maintain more vigor in the spur scion after full cropping begins. It would be hard to get it right without firsthand experience.

Many years ago at the orchard I worked at, we had some
spur type strains of McIntosh and Red Delicious. The trees
were not very dense compared to their non-spur strains of
these same varieties.

It was neat to see so many apples so close together with all the spurs. However, where the apples touched, they did not color well. While the yield per tree was high, the
amount graded out on the grading table was poor due to the skin color issue.

I do recall we did not have many of them as the orchard owner was not impressed with how slow the trees grew.

I too have always heard to use a large vigorous rootstock on spur types to compensate for this.

You always balance the two sources of vigor, root and scion. I bet you could avoid having the tree runt out if you managed it very carefully and thinned early, never allowing the tree to over bear or suffer excessive environmental stress (carbo starvation) from pests or drought. But do you need a tree with half the vigor of one on M9 with a more vigorous scion?

Thanks for the replies, sound like thinning properly is the key to managing spur varieties and that spur types are generally smaller trees.