The topic comes up several times a year--usually with one broker getting favourable comments following up one comment----normally a different broker each time.There is a real love-hate relationship with brokers it seems.
From what I have read over the years is that all should remember they are discount brokers and will try to do thing on the cheap to make their business model work---all will have good points and all will have weaknesses. It is only recently that TDW complaints have exploded upwards and out of proportion to anything I have seen.
BTW, I did move one account and found it was done in less than a day as I got a person who would do a wire transfer. Often the biggest problem is the time it takes to transfer with your account being untradeable during that period.
Also, the losing brokerage often tacks on fees so make sure the winning brokerage agrees to pay for these fees before you start.l