Actually, there is some truth to this statement. My experience with MRC's auto reversers was that they didn't work most of the time with steam locos. After some experimenting, I believe that these reversers only work dependably when the first wheelsets which cross the gaps (the ones that trigger the reversal of polarity) are involved in the picking up of power. My steamers with pilot wheels would fail to trigger the modules. I connected a lamp across the gaps of one rail and shorted the gap with a screwdriver. If the module flipped polarity, then the lamp should have gone on/off as I bridged the gap at either end of the reverse block. I found that using a screwdriver (or two, one for each rail) would not often trip the reverser. It might after a couple seconds (!!) However, diesels almost always worked. This admittadly unscientific method made me believe that only wheelsets conducting power would reliably throw an MRC reverser. I then bought some of Tony's reversers. These flip polarity when just one rail gap is bridged with a screwdriver. And I no longer have any problems with my steam locos either. There are the only two brands of auto reversers I have used. I believe the MRC uses a relay, while Tony's is electronic. Perhaps the key to a reason lies there.
An additional item: After years of faultless service, I had one or two of Tony's reversres start intermittantly failing to flip polarity, always on just one end of the revers block. I called and spoke to Tony, who sent me replacements at no charge (great service!) Unfortunately. the problem was unchanged. It turned out that the Atlas turnouts I used had developed high resistance in the rivets that conduct power, a few soldered drops solved the problem.
