I'm glad that some people are doing this. I'm sure that the results will be mixed, hopefully it will be more beneficial than harmful. I think it is fair to say that some dubs will probably never have their eyes opened and will just become more determined when they face "persecution". However, a few might check a website or two and start down the path of recovery. I think it is more important that newcomers to the hall and the general public are warned about the dangers of the Jehovah's Witnesses. The public usually thinks of Witnesses as minor nuisances and don't realise how dangerous they are.
I personally wouldn't be interested in joining this kind of protest, but don't want to criticise those who do. They may be doing some good, or if not, maybe we can at least learn from their mistakes.
I might be interested in joining a protest if certain conditions are met. These are just my preferences.
I don't like doing anything that will make people sympathetic towards the Witnesses. Protesting on their "holy day" might not be the best strategy. The special talk after the memorial (or any other Sunday) might be more effective. There is also the advantage that the signs could be better seen in the daylight and the dubs might not feel as persecuted.
I wouldn't want to join a protest that just advocates an alternate theology.
I would prefer smaller protests that seem less intimidating, something that makes it look like we are trying to educate rather than "protest". If a lot of people want to help, they can always distribute themselves among several halls.