I have used both the standard and plus (both cortex and non-cortex) extensively over the recent years.
I personally enjoyed the plus version more than the standard---more reach, and there was only a tad more power, but controllable power.
I've found that the plus helps to keep your swings sound and in check, since more precision is needed with a plus racquet. you get used to it very quickly, and it really helps your form, imo.
i suppose that if you're looking to tone down the power a bit, you should get the standard length. I've also found that the standard allows for more racquet head speed and thus more spin. That being said, make no mistake---the plus still allows for plenty of spin.
My two cents.