It would be easier on the devs and the users to implement divisibility.
Divisibility can always be worked into the way that the network works, however raising the total number of Safecoins (however it’s done) changes the core of the network itself; 4.3 billion - a figure that most likely will be hard-coded into the network.
Unfortunately for SAFE GB, it doesn’t solve the problem of currency circulation outside of network storage. There may still be the case where the value of Safecoins are too great to enable micropayments feasibly that isn’t related to storage. In that case one of the two options needs to be implemented, divisibility IMO.