It all depends on how close you are now to pedal strike. The longer arm will place the pedal lower as you corner, and you'll be more likely to bottom out. The thing is, 5mm is a very slight difference and you almost certainly don't come within 5mm currently, in which case it won't matter. Just understand that it will make the pedal stroke swing lower, and it's up to you to decide how much crank you can get away with given your bike and more importantly, your riding style. I used to cut corners as hard as I could and I'd hit 165s, with a track frame and narrow pedals. I've mellowed out some and probably wouldn't have any problems with 175s now.

There's also the question of how big a circle you can spin at a given RPM. I imagine smaller tighter circles are more conducive to high RPMs, so your gear ratio comes into question as well. Of course, again the difference between 165, 170 and 175 is probably small enough that you shouldn't overthink it.