Oren, As I mentioned in my last post, I believe that provided both
types of panels are getting the proper water supply from the pump, and
spray bar, I think both will do a pretty adequate job.

Whether which one will retain water longer, you might be correct that
the Aspen does, but will this make any improvements when the cooler is
shut off? I reckon we all can say no, it won't.

The biggest downside I've seen with Aspen, is pulling literal handfuls,
and handfuls of this nasty straw mess from the bottom of coolers, and
once this stuff starts running through the system, eventually everything
becomes restricted, and clogged, and it's usually the basket that the
pump sits in, and then onto the spray bar.

How many people's swamp coolers I've worked on to find this, and I would
correctly asume that with this swampy mess at the bottom of a swamp
cooler, this cannot be a healthy thing.
All it is then, is a breeding grounds for bacteria, and molds.
Something I surely wouldn't want to be breathing during the summer
months.
Mark