Stability yes, 'how fast it could deliver', no. What is more relevant is how fast the power supply can adapt.
What you are looking for is a PSU that can deliver the full 5V at 2.5A load, with minimal ripple. You also want a PSU that can adapt to changes in workload quickly without spikes.
We see it time and time again. People bought a PSU that should work, but it doesn't. A supposed 5V 2A/2.5/3A PSU doesn't cut the mustard. Phone chargers don't work. Powering off your TV doesn't work. Tablet chargers don't work. Because they never experience the same workload as OSMC, they're never properly tested.
We sell a lot of our power supplies because when people buy them they know they will work with OSMC. Guaranteed. Some suppliers say 'it works with Raspbian etc' but it's known that OSMC (and any other media based distribution) will consume more power because it is stressing the GPU as well as the ARM. We want to get the best performance possible out of Raspberry Pi, not the most power efficient, and we're not afraid to show up a few crappy power supply manufacturers / sellers in the process.
There's an easy way to get a stable PSU, and there still is. Some people choose to save a few pennies (but lose their time) in believing otherwise.