If he's sleeping through with the exception of an occasional crying out--which is pretty normal--I don't think I would confuse him by going back to 2 naps. What I would do is slowly try pushing the nap back so he's not overtired by bedtime. Most lo's don't do well with too much A time after nap and before bed so it's pretty key in the one nap transition to do early bedtimes to cope with overtiredness and to get the nap as soon as reasonably possible close to what it should be which is anywhere from 12 to 1. I think you are more than halfway there so I would at least try to push the nap back. If that isn't working you can always try the pm catnap but I would try for the later nap first.
