According to Robert11 :
On the inlet cold water pipe to the typical cylindrical, vertical, gas
fired hot water heater:

Are most plumbed in with a globe valve, so the water to it can be completely
shut off ?

They are plumbed with shutoff valves, and globe (washer) valves are usually
used because they're cheap. They should be done with full aperture valves, such
as gate or ball valves.

Gate valves are somewhat older technology. While they can
shut off completely (ours do), they're not as reliable as newer
ball valves, and these days ball valves are preferable, easier to use, and
usually cheaper.

Our new water heater seems to have a lesser flow thru it than our old one of
ten yrs ago.
Wife is quite upset.
On looking thru the web, I came across this gate valve picture.

So, which style is commonly used for this application, these days ?

Also, are these new heaters supplied with any kind of "Energy-Saving"
restriction like so many newer shower heads ? Any thoughts on why the
thruput flow might be lower on the newer one (same size, different mfg.) ?

When our water heaters were replaced, the installers replaced the shutoff
valve. They used globe valves, and discarded the existing gate valves.
Grrrr. That was the cause of the flow restriction, and I put the gate valve
back in.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.