I am not really an expert but I have experience. I planted two Dwarf pears and Apricot trees. My concern was, easy management. My Pears tree is about 30 feet now and silly me thought that dwarf could be no more than 15 feet. The Apricot and by the way is called Garden Annie Dwarf is about 25 feet and keep growing. I have Apple trees which stands at 60 feet I understand that. But the pears and Apricot at 30 feet is still too much for me to handle. I even got a tree service to cut 10 feet from the top of the pears but the guy was honest and he warned me that doing that will make the tree get sick and die so I chickened. I became to believe there is no such thing called dwarf. Good Luck.
Abe

I'm sure someone here can and will direct you to a link describing the differences between available root stocks. Choice will also depend on pest pressure of your location and whether you plan to irrigate. The longjevity of the trees shouldn't be an issue unless you're interested in leaving a legacy orchard capable of surviving over a century.

There is no need to grow 25' tall trees, even if you used seedling rootstock which is no longer widely available for apples anyway. However, something like M26 requires much less skill and time to prune than more vigorous root stocks. It is also more susceptible to drought and disease than other more vigorous rootstocks and often runts out without irrigation.

I like the idea of a tree you can climb in for kids but it does involve more work and patience growing them.

As far as the time required for fruit to bare- there's a tremendous difference from variety to variety and species to species.

Apples are the only fruit with truly dwarfing root stocks that I have experience with. Quince is the only affective one for pear and is tender in cold parts of the country. I've had good luck with plums grown on Citation.

I would check for sure what rootstock stark is calling semi-dwarf. I checked on a tree I planted 2 years ago and was told it was either on M-7 or B-118. B-118 would virtually be a standard tree. So check before you order the M-7 would be a lot easier.

I've got an couple of apples that are labeled "semi dwarf"...there is nothing dwarf about them! I'd say they are an easy 15ft tall (they need to be chopped back) and are 5 yrs old and have been pruned back in years past.

My technique is to plant standard trees and keep them pruned to the desired height. Misterbaby.