There are better alternatives than caulerpa. Yes it can go sexual and should be avoided IMO. Macros are a plant and do require a dark period. Running lights over it 24/7 actually inhibits growth. If you do plan on using caulerpa then I suppose running lights over it 24/7 would help prevent it from going sexual but what happens if the bulb burns out or you have a power outage? Your going to shock the macro and there is a good chance it will go sexual.
I have over 20 different macros in my system and the only caulerpa I have and trust is prolifera. Do yourself a favor and dont put any prolific caulerpa in your system. Not trying to undermine anyones way of doing things but caulerpa is a ticking time bomb and it just takes 1 changing event in your system to tick off the caulerpa and wipe your system.
As far as nutrient uptake, its best to have as many different macros in your system as possible. Macros typically have 2 different ways of uptaking nutrients, steady and burst. Chaeto has a steady nutrient uptake and is good over time. Its also good to have burst uptake because when you feed there is a influx of nutrients put into the system. The burst macros help bring those levels down quicker. Not sure which macros are burst, hence why I recommend multiple types of macros. Red bush hayi, gracilaria mammillaris, turtle grass (if you have a deep sand bed in your fuge, 6+"), violet dreams, red gracilaria, etc, are all good at nutrient uptake. The more varied the better your export will be.
I personally cant stand chaeto. I had it at one point in my system and still to this day I am pulling clumps of it out of my fuge every month or so. It is good at nutrient uptake but its a freakn weed and there are much prettier macros that do the same thing.
Here are pics of my 2 fuges. Much better than a wad of chaeto IMO