The difference is very minor. Measured in cm, which is a fraction of an inch. I think people make way too much about having a perfectly sized bike. Ride the bikes. If it is comfortable, then you are fine. Even if it's not "perfect", you can adjust the seat in three vectors, change the stem for $20, and adjust the bars to compensate for the different size frames. You probably would not fit on a 60cm, but if you used to ride a 52, then I don't think a 53, 54...maybe even a 56 would be out of the question, especially when one brand's 54 is the same as another's 56. Don't get all wrapped up in a number. I don't think you will notice any difference between a 52 and a 53.