It complicates things slightly to have two different delays, since you would then need two different historical median calculations, although they could work off the same feed history.
24 hours to me seems like it would be fine. I'm not really sure what problem was allegedly solved by changing it from the 24 hours in Bitshares, particularly since as you say there wasn't any.
BTW, on your earlier comment about the pump ending in 3.5 days (or one day or whatever) just as the conversions come through, if that did happen I would consider that a success! The bigger issue we've had is pumps that persist for weeks or months. If we're reduced to worrying about 3.5-day pumps, then we are well on the way to getting the price stabilized.