Pierced, I m not sure abt other medela pump models. But for freestyle, I m pretty sure. Cux I was told by medela salesperson Tat d connector plastic mould is v soft n by frequent sterilizing, it will expand n contract easily. Hence, losing it's grip n thus d suction.
If u intend to latch, then I guess single is fine. But if u r a 'heavy pumper' like me.. Then it's better to use double. I was pumping 8-10 x a day during the 1st 2.5 mths. Can't imagine wat will happen if I m using single pump.
However, I know of a few ivf mummies who are looking to sell their preloved FS. So if anyone is keen, let me know