that is a matter for discussion. You have a few days to decide. So that allows you to get input from a few experienced SOG'rs before you start decapitating.

There are different ways to go here...and the Pros/Cons of each:

1. Not topping. This is easy;
Pros: No stress, More breathing room, due to taller plants. Big Fat kolas

Cons: Potential loss of light penetration, (You lose 1/2 of your lamps strength in lumens for every foot.
If you have growbox height issues, then you may have to manipulate your plants by tying them off here and there.

2. Topping. Same old story...
Pros: Lower profile for better light penetration, more budsites

Cons: Stress.
Could have environmental issues (air circulation) to due lack of seperation/space underneath canopy. A porblem in dealing with and providing a haven for pests; Should they find their way into your medium.

Now this answer is squewed towards your current question/situation. I addressed this reflecting your mention of an over-planting issue and most likely small concerns either way...well except for the pests. lol later.

Next!