I don't know about that variety but my Alphonso arrived Dec 2014 with a few leaves like that and it is not yet to the top of my 6' fence, though I have lightly pruned just one or two branches at the top, twice--but it has spread sideways a fair bit. But then I live in a ridiculously cold climate to be growing mangoes and I'm sure I get far fewer growth flushes than in their native climate. Seems to me you've got a good start there. One thing to know: you'll get a single limb growing from a single leaf node, but when you have a circle of leaves you get a cluster of new branches starting and they grow outward from there. They start out reddish on rubbery stems (not for more than a day or so on those stems, get to it fast if you're trying to redirect any direction of growth there), then light green leaves, then dark green leaves on solid wood. Mine just started pushing out a growth flush after last week's 100F+ heat wave here in northern California. Here, let me show you a few pictures of mine. Jan. 10, 2015, with a first circular spray of branches starting to sprout like yours did, (with Christmas lights for warmth with nothing but that one straight-up whip to wrap them around) and just now. Birdnetting at the bottom is to try to discourage the cottontails that show up. Seems to work. The squirrels still think the latex in the sap smells bad and they haven't gone near the tree once. My pomegranates, apples, peaches, cherries, plums, figs, they're all over those, but not the mango.

We've got K&T in our 1919 bungalow. We've had two licensed electricians (one my uncle and the other a trusted friend). Both assured us that our wiring was in pristine condition. Since it's not exposed to insulation, they said that we wouldn't have any problems. I talked to our insurance agent who didn't seem to care about the K&T. That said I'd replace the stuff if it didn't mean destroying the plaster walls in the house (or cost a fortune to maintain the plaster and run new wiring). We did get an estimate on running new wiring, but it was $89 an hour with no assurance that he could maintain the plaster walls. That price didn't cover any incidental damage to the plaster nor necessary repair should he need to cut into it. He was unsure of how many hours would be required, but he assured us that it would be many.

Knob and tube was designed and installed when codes were more conservative. Generally the workmanship is superb - the electician knew how to splice and solder and tape properly. I've inspected the K&T in my attic and it all looks great. Insulation is not brittle or crumbling; no sign of overheating. Some of it has been replaced with entirely new circuits to the remodeled areas of the home. But what remains is in great shape. A problem comes when homeowners or unlicensed electricians try to splice into existing K&T to add more circuits. Either the connections are bad or the original K&T is overloaded. The proper way to add new circuits is to put a new breaker in the panel and run Romex (or armored cable, or wire in conduit) to the new locations. Another problem area is the dual wire pre-Romex that is actually wrapped with a rubber compound and fabric. The rubber tends to dry out and crumble with age. If disturbed, you can wind up with a neutral and a hot wire getting bared in very close proximity, perhaps contacting each other. This stuff should be replaced with Romex - providing the splicing into the old K&T that feeds it is done properly (as in a distribution box). My understanding is that the flying splices traditionally used in K&T are no longer allowed on new wiring.

According to the Ontario Electrical Safety Authority "Myths * Knob & Tube wiring is unsafe. * All knob and tube wiring must be disconnected and replaced. * The Ontario Electrical Safety Code no longer recognizes knob and tube wiring as an acceptable wiring method. Facts * Knob & Tube wiring is safe, provided it is properly maintained by competent licensed people as outlined above. * The Electrical Safety Authority as well as the Ontario Electrical Safety Code recognize and accept knob and tube wiring methods. * The Ontario Electrical Safety Code 2002 edition contains rules that govern the installation of open type wiring methods (knob & tube). Rules 12-200 to 12-224 set out the minimum safety standards for the installation of open wiring, which may still be installed to this day." Nevertheless, the practical reality is that, depending on your jurisdiction, many/most/all insurance companies will not cover you if you have k&t installed. Furthermore, if you check the restrictions on k&t in the linked bulletin, you will see limitations that make its continued use impractical, costly and inconvenient for most families.