I'd like the idea with NZXT grid but only the device itself would cost me 50Eu or so... Also Argus Monitor is basically speed fan just better optimized currently and I wouldnt want to have problems like with speed fan... Also is it worth to change all fans to BeQuiet pure wings with PWM and try that first or I should just bite the bullet and go with smth like NZXT?
I don't think changing fans to PWM helps much. Only if all headers on your board have full PWM support. As owner of Gigabyte board, I'd say answer is no. Grid 3 does support PWM fans, if memory serves, so you can upgrade fans later.