Without knowing the actual local procedures used by the company we can only surmise that having a departure and climbout path that has to cross an arrivals and approach path is not the greatest idea unless you have planned vertical separation as well.
Ie, arriving aircraft stays at 300' until he has positively identified departure aircraft and departing aircraft climbs to 200' until positively clear of the arrival path.
Having no crossing would be ideal but sometimes the wind conditions probably won't allow for that.
I was thinking much the same thing. I had a look at the various "tours" they operate and I'd say that the most popular ie the cheapest ones, all tend to depart and track south, then reverse back north along the coast before tracking back down to the pads via the Broadwater. I'm assuming it is the way it is is because finishing via the Broadwater gives them a better approach to the pads. I wondered if reversing the "circuit" might provide some relief, but it just reverses the problem. The southern pad departures would cross the northern ones approach. Arrivals and departures from the pads to and from the west so that some form of pre-arranged vertical/horizontal separation would probably waste too much time when you are trying to sell and achieve as many 5 minute flights as possible. I would imagine the only way to eliminate crossing paths is to not use two different pads.