So why the 18500 over the 18650? Just curious...
Just my personal preference. I think it looks a little better proportioned and handles slightly better.
It's just a perfect size mod imo.
The weight and balance just works in my hands better. With the P+18500, I can use the regular or heavy spring depending on what is needed (gloves during the winter), where I have to use the heavy on the P+18650. The 18650 is great for battery life, but the 18500 just feels right all the time.
Although, P+18650 with an 18490 and Kick does feel quite a bit lighter and easier to handle. Might sound odd, I know.