Yea, still gonna stick to the naos, I prefer mice that have a pinkie rest, the Castor is not my cup of tea. Just waiting for a newer Naos to come out, pretty sure they show cased one that has a built in heart beat sensor. Though it seemed superfluous, I always thought it'd be funny to see how fast my heart races in intense games.
I am in similar situation and I can fully agree... after seeing videos on new Mionix Castor mouse, I stumbled upon Mionix Avior 7000 on sale for half a price. Its really nice mouse, build quality, software, everything you mentioned I agree with, but the size is like for a child dwarf. I love the 2 buttons on each side of the mouse, but Im afraid I will not stick to this one for too long. Just be aware when you start thinking of buying one and try it before you do for sure.
I was actually very excited when I saw the Castor. I own the original Naos 3200, no RGB, "only" 3200 dpi, less buttons, less lights, basic. I love it, but it is actually annoyingly long for me. I use fingertips to move around, so the lightness is welcome and the pinky sapce is great but the castor looks like exactly what I want. Unfortunately for Mionix, their build quality is great so I will not be upgrading for a while till I kill this one.
If I could take the hump off the top of the Naos, make it a little shorter and move the side buttons back further I would so happy.
A friend bought one. The wheel is loud as hell when scrolling down. We thought it was just a bad batch, sent it for a replacement, but the second one has the same issues. I've only had a mousewheel as loud on an old cheap logitech office mouse :| He also didn't like how soft the button clicks are, but that's personal preference. I'd suggest to try it in person before buying.