I can only tell that if You try pirelli diablo scooter You will realize what I am talking about. Kendas are like plastic. You can not even compare kenda, maxxis with pirelli or bridgestone. I prefer pirelli because diablo scooter series are more round.
I have never driven a scooter with Pirelli Diablo so really cannot compare. Yet, I am a person that drives 365 days in a year, including winter, heavy rain, night, snow and even ice a few times and it is my opinion that Kenda tire I have on People 250 S is an average touring tire.
Also, I prefer to compare models of tires, not manufacturers and critical for me is how the tire behaves on slippery road and in heavy rain (every day on my way to work I have to cover 13 kms of downhill/uphill twisty and slippery road with bad irrigation and literally rivers of water running downstream so it is crucial for me to have tires with good rain-handling - this is also why I replace tires when they are at most half way through).
OEM tire on Agility 125 is also quite good but it is a shame I cannot remember the brand (it is not Kenda).
Slovenian company Sava (
http://www.sava.si/eng/ ) makes excellent and inexpensive performance tires for scooters, from 10 inch up and I have been using their products for years on my scooters as replacement. I hear they were exporting tires to USA too and have also some products in the sports range. I recommend those tires, provided they can be purchased in your country(ies).