I've been disappointed in the few multi grafted trees I've grown in the past. Always one variety wants to become the main tree and the others become small twigs or die off all together. Some people are able to maintain a variety balance with regular and rigorous pruning, but the tree isn't happy with this.
The nice thing about them is that you get to try several different varieties of fruit for a year or two, see how they grow and ripen in a specific location and can judge which ones you like best. Then get the trees you like best and grow them on their own, letting the dominant variety graft on the first tree take over.
I grew a Zee Sweet Nuggets Semi-dwarf Multi-Budded Pluot tree. I liked all the varieties and they produced well here. When Geo Pride took over the tree, I bought Splash, Emerald Drop and two Flavor Grenades(my favorite) to plant around it. Pruning is difficult each year to keep them in their space, but I’m getting more fruit than I would have trying to make peace with four varieties at war with each other on one tree.
I grew a five in one cherry tree that had nice blooms each year but no fruit. I was told that I would get a crop every few years, but it didn't happen. I learned that we didn't have the chill here for those varieties of cherries. It was replaced by three crowded low chill cherry trees that are the first to produce beautiful heavy blooms each year and drip cherries.