There are a lot of reviews online. .. you may want to take a look there. I met a go pro user oversea n he says that SRP is better. I have seen the effect which is not bad but since this is not my personal experience do take his feedback with a pinch of salt.
I have used Polar filters, one with macro and the other just the regular. I seem to get round spots when I do underwater filming at certain angles only.
I'd say go with the cheap one! The macro lens didn't do much for me.