A cautionary tale and call for advice:

I'm doing a full tear out replacement with aluminum clad wood windows.

Some research on the internet turned up Marvin, Weathershield,
Jeld-Wen, Hurd, Semco,
Loewen, Peachtree, and Kolbe as making aluminum-clad wood
gliders/sliders.

In the process of vetting about 10 installers in the DC area and
hitting window showrooms, Home Depot, real lumber yards, I had never
encountered an actual glider until today. What I heard is "the
construction is very similar to this double hung I can show you", which
was sometimes accompanied by the salesman turning the double-hung
sideways and moving it back and forth, saying "see?"

Well, it's not the same, to state the obvious. To begin with, in a
slider, gravity pushes the window against the track, but in a DH,
gravity pulls it across the track! Furthermore, confirming by
inspection that a company makes a good double-hung does *not* indicate
they make a good glider.

For example, I thought the DH Weathershields I had seen were passable,
but I finally tracked down a Weathershield glider today and what a
piece of garbage it was! Standing directly in front of the window, I
had difficulty getting it to slide open. First it was hard to budge
and second once it budged it kept bucking -- catching on the leading
edge and rising up on the trailing edge. Plus the cladding job was
abysmal.

OTOH, I leapfrogged the local Marvin showroom, where they don't have a
glider, to visit the one in Northern Virginia where they do have one,
and it's as well-made as everything else by Marvin, for whom I do not
work nor do I derive direct or indirect benefit from plugging them.
Part of the reason for the smooth operation is the fiberglass strip
inside the groove in the base of the window that runs along the track.
What's more, I called Marvin HQ and a nice Minnesotan spent twenty
minutes on the phone with me explaining the finer points of their
construction, gave me his name and direct number and told me to call
back anytime.

After calling dealers listed on their websites, I've concluded the rest
of the clowns mentioned above don't bother making examples of their
full line of products available in the DC area.

If anyone knows differently and can point me to a showroom, I'd be
delighted to check them out. I'd love to discover I have options for
a decent aluminum-clad wood slider other than Marvin, since Marvins are
very dear, but I have to be able to hold the competitor in my hands. I
won't drop $20K installing a product in my house sight unseen.

Cheers,

ccsikyr