in this case there is really no difference, especially if Site contains all
the values
that were originally in the file with define directives, the structure is
essentially the same.
if you are going to have just one class contain all of the configuration
values
there wont be much difference from using define directives. one thing
about
define is its notoriously slow, so you would have that advantage.
generally, a benefit of using classes w/ constants is the namespace aspect.
so you could have Car:

EFAULT_COLOR and Plane:

EFAULT_COLOR
for example, but again, how much different is that from
define('DEFAULT_CAR_COLOR', 'red');
define('DEFAULT_PLANE_COLOR', 'blue');
i dunno. to be honest i typically use a mixture of both approaches. class
constants
for classes when they are appropriate and define directives for global
configuration
values.
strictly speaking i dont think having a class of all constants qualifies an
app
as 'more oo'; id say in java for example you simply dont have any other
choice.
-nathan