Well, if you're just a casual gamer who plays a few rounds of CoD every now and then, it won't really matter. However, if you play well over 500h of BF3 for instance, you will most definitely notice the difference between 1ms and 8ms, or feel it rather since humans can only notice a difference greater than 30ms. Yes, contrast and colour reproduction are better on IPS panels, but then again, it's not really relevant for gaming unless you're playing slow-paced games exclusively. Responsiveness is the only thing gamers need to look for in a monitor.
Frankly it makes no sense to use a photography monitor for gaming. BenQ and ASUS monitors are tailored towards gaming, go with one of them and you'll be fine.