I've seen and heard the exact opposite of Slo-bo.
I saw one at Bedford last year that would not read the same speed twice,over about a 15 shot span it had 12 or 13 different readings and some of them were within 15ft fps of each other.
Let me point out that when I first saw it,.... it was not on the market yet so it may have had problems that they have repaired by now.