Bigger pinion in stock motor is a bad idea, new esc or not. If you have the thermal headroom, you can.
The max6 let's many more pixies flow vs the stock orange esc or max8/8bl150 for that matter. Its not even comparable. Can't compare vs the stealth esc just because I don't have one.
Normally I'd agree a bigger esc dosent make a big difference, but this one does. Not sure if its more amps, or it ramps up the power or has a significantly better response, not sure. Either way it feels like you dropped in a bigger motor.
I'd likely change both esc/ motor at the same time; and least then I have a funcational backup versus burning up the stock motor for the sake of trying it.
I'll mention one last thing since all of my last 4 ESC's have been sensored(Max 5G2+, Max 6g2, Max8G2S, MMX8S).
Spend a little extra and pair it with a sensor capable motor, everything runs more efficient/quieter/smooth low speed operation and it will prevent overheating/damage should a bearing lock up in the drivetrain. I've run plenty of the clones from china(rocket/surpass/xteam/hobbystar) and they aren't bad options, except when you need all of the nice sensor capabilities.
Edit- You could run a Max6g2 ESC with 4278 EZ Run motor up to 6S, the sensor plugs are universal.