And it will be unreliable as long as vital parts aren’t swapped. The general consensus on here is going to be that it’s not worth the hassle. By the time you replace everything that needs replacing you’re pretty close to a decent diy build anyway. That said …
As far as why things are different, well probably just because the manufacturer sourced cheaper parts elsewhere over time.
Nice job on swapping the esc. Those numbers you mentioned are insanity! Any idea what kind of battery is in there. Careful with no name boards using cheap bats that will endanger you and yours. Sounds like you’ve had good luck so far but I would look at the cells of you can get in there.