So much lack of hard evidence on how to go about trying something new with new rootstocks in pots. When I first set up ground in Vancouver in 1990 right when I started with home depot apricots, which forced me several years later to start listening to locals, I started along with a better idea than apricots that maybe you would still enjoy;

On the idea from a brand new general applications of fruit trees book, one of the inclusions were by Sam of Raintree nursery that I thought at first was a misprint. It stated in short order "asian (nashi) pears grafted on quince are 5-10%". (very short and sweet)

I went on to list with the discussion group NAFEX and found many participants there were actually established nursery operators, one being Ed (?), who for sure owned Rocky something nursery before selling out. He had verified he had grafted these asian-japanese-nashi pears to quince. They were in fact as the book indicated small bushes. 

He seemed very convincing there were no issues with the graft incompatibility syndrome John had talked about with his two so I ordered a bunch of quince-C rootstock and picked what seemed to me the fastest growing asian tree of 180 young self rooted seed selections. My final desire was to have at least one fence line of privacy asian pears. I guess that was a combined experiment that worked really well, as they did not have to be in pots and they could have reached maybe 7 foot and stopped growing. Just like Ed said would be true, and lots of production as promised.

Being older I now I began removing them one by one to cross section (test) the asian/quince grafts which were always good. One remains since it is kind of attractive and still no overgrowth above or below the union. However I keep ignoring the fruit as I usually find it slightly bitter by comparison to the same clone in my yard on it's own root.

I thought the whole story should be told since it is sometimes the species on the top and above the graft  (not just the root) that can have the dwarfing influence geatly magnified..

GH,

An apple tree grafted onto the extremely dwarfing rootstock EMLA 27 (virus-free if truly EMLA) or M27 (--secondary source and not guaranteed virus-free) will require a lot more care than most any other apple.  For starters, it should be planted into a soil that is thoroughly amended with the appropriate elements for a well-balanced soil (--get a soil test from a reputable place).  Secondly, it should be staked for appropriate support against our occasional wind storms, and against inebriated sasquatches that might stumble and fall against them.  Third, they should be given absolute loving care and appropriate, judicious pruning to promote good, well-spaced, firm branching for subsequent fruit production.

The main factors in dealing with an extremely dwarfed tree is the support, and the fact that the tree -- producing normal-sized fruit on a dwarf tree -- will need the utmost attention and the necessary nutrients in the fertilizing regimen to perform appropriately.  

If I were you, I would not keep the tree in a pot unless you have no choice.  Years of experience suggests to me that a plant's ability to "spread its wings" once out of a pot can truly bring it to life.  We all love freedom.  With an apple, planting it outdoors would be fine.  One of the selling points for dwarf fruit trees of any sort is that they can supposedly be grown in a pot indoors.  This may be the case for people who just want to have a particular type of fruit tree represented inside their manor, but if you really want it to be worth the purchase price the tree should really be planted outside in a good, fertile soil so that it can produce a healthy, broadly-reaching root system.  If the soil nutrients are inadequate, or the root system is constrained, the plant itself cannot be expected to perform well.  

'Hudson's Golden Gem' is a local and regional Classic.  My personal recommendation is that you select some scion wood from it within this coming month and put it, in appropriate form, into the fridge, then graft that onto an MM106 or MM111 rootstock in late March this spring so that you can get a larger tree and truly appreciate the cultivar in the future with each apple and each and every bite.

Reinettes