In 2018 I grafted three varieties onto my mother Lang tree–Redlands #4, Xu Zhou, Shi Hong. This multi-graft tree has the highest fruit-set I have seen to date, and this is true across all four cultivars. Perhaps this is just a coincidence.
Redlands #4
Xu Zhou
Shi Hong
Lang
As far as flavor goes, it is a coin toss between Xu Zhou and Redlands #4. Size goes to Redlands #4. Bother cultivars have a honey flavor. I am not the best at describing flavors.
I have three varieties grafted to my Lang. One fruited on a short graft (turned out to be a different cultivar than I thought I grafted but all is good) but the other two have not fruited. R4T3 had a couple of fruits that dropped and Coco did not even bloom that I remember.
I have Xu Thou and Redlands #4 that are both full of fruit but neither have ripened yet. I think Redlands will ripen before Xu Thou. In comparison all my other cultivars are either full on harvest or just beginning to ripen.
How large are the grafts on your Lang tree? Each graft I mentioned above are 4-5 feet in length aside from the Shi Hong (2ish feet), which has the least amount of fruit.
With my three varieies, Honey Jar (2017), Sugar Cane (2016) and Shanxi Li (2016) share the same location, climate, fertilizer, watering, they vary greatly in fruit setting.
All flowered heavily.
Honey Jat, though the youngest set most fruit.
Sugar Cane surprises me by low fruit setting this year (last year was good fruit setting) .
Shanxi Li set the least, every year. No surprise there 
This year I grafted 2 varieties on HJ, 2 on SC and 15 on Shaxi Li.
I may graft HJ on a Sc and SL just to increase the chance.
I grafted what I thought was Li and it turns out to be PROBABLY sugar cane. The graft is only 6-8 inches long and it had 4 fruit…three of good size. Coco graft is probably 2-1/2 foot growth and very healthy looking. R4T3 is about 15-18 inches. It is the weakest graft and the wood is thin. It did set fruit as it did last year when grafted but dropped all the fruitlets at a small size.
