I would think the longer riser and shorter limbs allow for a bit more speed, more early draw weight etc.. I personally prefer the longer limbs with a shorter riser, I don't care for bows with a lot of early draw weight. Love a bow with a soft feel in the early stages of the draw.
I also build a 52",54" on a 15" riser, the 56", 58" and 60" on the 17" riser. I also build a 62",64" and 66" on a 19" riser. By using different length of wedges they all seem to work well for me.
Thanks for the compliments.