Thanks for the great info on air layering Simon! I'll let all 3 air layers grow. The fruit is my favorite! I know most people don't rate emperor as high flavor wise, but I've had it side by side with mauritius and brewster, and I prefer emperor. They are tart if picked underripe though. When perfectly ripe, they have a tiny bit of tang left but mostly sweet, and when slightly overripe, they are all sweet. Tree was loaded this year and I started selectively picking just when they started ripening, each day picking off the ripest ones. They also hold on the tree for a little while because of that tartness which is great for dooryard growers. Since they don't keep fresh once picked, the tartness lets me leave ripe ones on the tree and they will stay nice flavored for about 2 weeks past when they were ripe to pick. All in all, I got about 20 days of consecutive harvesting from the tree - most days picking around 2-3 strawberry containers full.
kc_moses & Ethan - I planted this tree in ground in 2009 and this is about its 5th year fruiting. It could easily be 15' tall by now, but I prune it hard every year to maintain this shape, which is just small enough to go under a frost shelter erected around it in winter and to keep fruit within reach for harvest without needing a ladder. Here's what it looked like in 2011 when it was 2 years old so you can compare what it looked like before it matured.