As they don't keep the ants cool enough even running at 190-200 gh they are only at about 34 with the new fans, I run two fans in case one cuts out, thus the ants don't cook them selves.
Also i'm not to sure how reliable they are, I've chosen a fan that I know is regularly used on servers and has a good reliability track record.
That hasn't been my experience. The speed of the stock fans is controlled by Ant's controller board based on the reading from the on board temp sensor. The stock fans never even run at top speed in my experience you can test this by unplugging the fan control cable and your fan will accelerate to top speed which is considerably higher than it's normal speed.
At any rate, it's your money but I don't see any reason to believe there is a benefit to this.