Hi Steve, I'm in NM, and familiar with Swamp Coolers, and work on them
all the time.
Gotten pretty good at it actually.

As far as synthetic panels versus Aspen Straw panels, I myself really
like the Synthetic Blue stuff the best myself. they claim better
cooling with most synthetic Panels, but in all actuality, there's
probably not a heck of a lot of difference.

The downside with Aspen Panels is the tons of Straw Crud that always
accumilates in the bottom of the resovoir, and if the Water Pump Clogs
up, then it can't do it's job of Pumping, and Spraying Water onto the
Panels. I've seen this stuff clog up the entire system from the pump,
and particularly the Spray Bar-Spider.

The old Round Swamp coolers can really be a headache, with the round PVC
Spray Bar, that has numerous little holes drilled into it.

The Spray Bar must provide full flow for the Swamp cooler to work it's
best.

Soft Water versus regular Hard Water? Well I'm sure the soft water has
to be a improvement versus the hard, as the PH probably isn't as
alkalinic with soft water, and thus there will be less build-up of
deposits. Water in NM is generally loaded with Caliche, and the only
thing I use local water supply here for is Bathing, Brushing my Teeth,
the Swamp Cooler, and the garden-lawn.

Having fresh water flow in constantly I suppose could be an advantage,
but here in NM, generally during the day with high heat, there's plenty
of evaporation taking place anyway within the swamp cooler, and the
float is usually always-a-trickling.

I find that here, one cannot go an entire season without periodic
service, draining of the resovoir, and using a cleaner-conditioner, and
once flushed, I then use an anit-bacterial liquid, and i also place a
condistion block in the unit, but most of these methods only seem to
help little. Things like water filtration, and soft water I'm sure would
make much better improvements to staving off sediment, and scale
build-up. Here, I'm generally replacing Pads-Panels once a year, and
due to many nasty dust storms we get over here, I try to stay on top of
Resovoir maintainence. Deifnitely do make sure your Pump sits in some
sort of Basket, and if you can, pullit periodically to clean with an
acidic product. Believe it or not, I use "The Works" Toilet Bowl
Cleaner on the pump's bottom grids, and the Basket. When the basket
looks really poor, dump it, and replace, they're only $2-$3 ea.

A Spider Snake can come in handy to clean out clogged water tubes, and
do make sure proper float level is correct for your unit, not too much,
or too little.

I'm typically up on my roof doing this 3-4 times a season to get optimum
performance.

With whole house Swamp Coolers, I had found mine was seeming to give
awefully poor air flow, just not enough ommph. What I did, was I
replaced the stock pulley (12") with a smaller 10" Pulley on the
Squirrel Cage. This helped by causing the squirrel cage to spin faster
on either Low-or High Fan Speeds. (just like gears on a racing bike)

To then find the correct size Belt, all one has to do, is take a string
to measure what the new belt needs to be for the new Pulley Combination.
Tie the string in a knot, slip it off the pulleys, and then on your way
to the local retailer.

Belts come in every size imaginable. of course there's a point one
cannot go beyond woth Pulley swaps, as the motor may then be placed
under more strain.

After any service is done, I always make sure that I leave one panel
accessable, so I can see how everything is working before I button it
all up, and come off the roof. One time I didn't do this, and the Hose
going from the Water pump to Spider was pinched by one of the panels on
my Square Cooler (Hose was a bit too long)
I was wondering 'hey. it isn't that cool in here!?"
Hope this helps you, Mark