well, some things to consider:
- how much production ability would you be losing if you cut that big healthy leaf off?
- since you're using CFLs, the light penetration fades very quickly. will it be worth the sacrifice of a closer, healthy, larger leaf to try to promote further away, smaller leaves to grow more?
generally, i just try to LST big leaves out of the way. or if they're very old and far away from lights, i will cut them, regardless of whether they're blocking anything or not.
lastly, understand that those lower leaves are going to grow no matter what, and the direction they'll grow will be upwards. whereas the big fan leaf really can't grow up at all. so, they may just catch up and surpass it anyway.
...enough to think about?