Here are my thoughts. Just remember, my banana knowledge is minimal and I have been growing these for only about 6 years now.
If at some point your main banana flowers that banana will die.
I always like to leave one or two pups around the oldest banana so that when that does happen I have one waiting in the wing to take its place.
If you do remove the banana pups I havent seen any difference in the main plant after removing the pups.
If you want to grow the pups that is where you will need to be careful in how you remove it from the main plant.
Unless you dig down and under the pup to see if it has roots you are taking a chance with getting it to grow. I've had a hard time getting the pups to grow without the roots. But it is possible.
And you need to make the cut really close to the main plant to remove the pups in good condition.
But if you are just looking to thin out the pups get yourself a good prunning saw and cut away.
You might want to leave the exposed cut open to the air for a day or two to let it heal. It happens pretty quick with the orinoco's so I imagine your Gran Nan should do the same.
