Hi again
for simple current & power check have a look at these review videos for Watt meters.

i just bought one (€12.00) and it works a treat.
Whatever the label says they all seem to be made by Busing!
Cheers Doug 😎

I do believe you have answered the problem when you mentioned the size of the props and motors. They may well be capable of supplying the power but that comes at the cost of higher amps. if your original 50 amp blue controller eventually gave up then a 15 amp Mtronic will struggle with just one motor and be totally overwhelmed with two motors.
As Doug has just posted you do need to get a wattmeter otherwise I suspect you will be cooking ESC's on a regular basis.
Experimentation is fine but it can become a tad expensive if you do not have the right tools to help you make informed choices.
dave