I haven't tried reds because they are ridiculously hard to find here (most likely will have to import), however I am pretty happy with blacks. I prefer the harder keys to super soft ones not because of maximum speed potential, but because I use my keyboard for more than just gaming, and super light keys might get in the way.
On the other hand I am very happy with them because my own speed is good enough (can stream extreme BPM without much issues), but on lower bpm I prefer harder keys by far. It just feels much better streaming 120~140 bpm on harder keys (I wish they were harder actually) than on softer, but I guess that could just be me.
There is no doubt that reds will yield in a bigger stamina pool for reasons Wishy already stated, however I believe there is more to it than just pure stamina/speed which is the reason that I don't want to switch to reds (I would like to try them though, just to see for myself).
I have tested blues in the store I was buying my blacks at and I can say they are disappointingly bad, at least in my opinion. The keys feel weird and pressing them feels weird. I know this is personal preference and pressing those keys felt like my presses are getting interrupted, that just didn't feel right. Also most popular blue keyboards (blackwidlol) have insanely bad build quality and probably bad rollover (my keyboard has NKRO, vs blackwidlol's 3KRO).
Sorun wrote:
b-b-but blue master race
Unless you want to share your thoughts in a more descriptive manner which describes why are they superiour, I would probably say that you might have bought the wrong keyboard.