the Castle Neus are hand assembled in China whereas the Tekno Neus are hand assembled in the states. Both are great motors. here are the motors i have owned and my experience.
1512 1.5D/F Neu
1515 1.5D/F Tekno Neu
1515 1.5D/Q Tekno Neu (Q means sqaure canned)
1515 1y Castle Neu (just got today)
In my experience the Tekno Neus have been better than my regular Neu. Just seemed more smooth, faster, etc.
So here is what led to my questions;
I like a really fast setup so i run my 1515 1.5D's on 5s. My temps stay below 150 and it has seemed like a all around great setup. Then my friend comes over with his new Castle Neu and it is just as fast as mine. I was surprised! I thought with 2200kv it would be slower. So then i wonder, is the Castle Neu a better motor or is 2200kv just more than enough power to get the speeds i like and the 2700kv isnt adding much? So i start thinking if i can get the same speeds and power with the 2200kv and have lower temps then why not. So i am thinking that the speeds have nothing to do with the Castle motor as much as the fact that 2200kv is plenty for what i want.
So now i am in the process of listing my 3 Neus on ebay to downgrade to the 2200kv motor. i would just keep the Castle Neu but i really like the square canned Teknos more than anything. that said, i like how castle has made their motor leads longer so there is no need for extra connectors/resistance and you can just plug straight to the ESC.
My wish for the perfect motor is a square canned Tekno Neu with motor leads like the Castle both in length and how they are completely sealed off. The tekno design is an improvement over regular Neus but castle made it better still. the tekno design can still let dust in. like they say, "if you can build a better mouse trap, people will buy." its kind of a trade off for me. either i sacrifice the square can that i want or i sacrifice the motor leads that i like. why cant i just build my own damn motor????!!