I have a Dave Wilson multigraft and a Tropic Snow, both are in pots. I've had the multigraft 3 yrs and it has about 2 dozen fruits (all 5 varieties are fruiting this year for the first time). The Tropic Snow has about a dozen fruits and I've had it 2 years. So young trees, but they look like they are going to be fine in pots, may go to ground this year, have to wait and see.
If you are not hitting the chill hours for the variety, you won't get fruit.