You say you have a slow letdown - I would consider a pump that has the funny little sucks to stimulate a letdown, or at least has a variable suck strength so that you can start gentle and then turn it up once things are flowing.
Do you want to be able to pump both sides at once?

The advantage of the hire pumps is that they are powerful, and can get more out than a little pump - so for supply stimulating you will do better with a symphony or a lactina or similar than you will with a little pump. And then hopefully after a month or two you don't need it any more.