I have the pintail smock, bought a few years ago, it's okay but as Rich says the outer fabric becomes saturated very quickly, doesn't let the water through the inner membrane of course, but the outer becomes wet and heavy and cold and soaks anything else you come into contact with like a seat for example. I keep it in the jeep now just as emergency backup.
Recently got the monsoon elite 2 to be my main wet weather choice and the latest version is very light and packable, and the outer will repel the weather as the fabric is different to the earlier pintail and other versions. Haven't used it in anger yet but expecting it to be pretty good, breathability having supposed to have been greatly improved also.
Be wary of folks talking about earlier versions as they have upgraded the various models over the years to address some early issues. With that in mind the current pintail smock might be different to the one I have, I don't think so, but not certain.