Often its worth reading posts a few times so you dont miss things, and sometimes we make typos, I have edited the paragraph about wemo/CS fans as it was less than clear in what I was trying to say!

I dont think anyone was talking about the wemotec fan when it comes to how much Kv, 4100Kv is fine in the wemo, I run the 1W30 in the wemo on 4s and used to run the 2848-1 on 4s, its a 1400w odd setup that puts out 2kg+ of thrust. What was said was 4100 was too high for the CS fan, reason is because it presents a huge load to the motor compared to the wemotec rotor. You have to use a lower Kv long can motor in order to maintain efficiency turning that highly loaded rotor.