As Glenn told, the PGL-III-C are all overspec - they have the biggest space for conducting away the heat.
I personally don´t like the big host, this is why I decided to go with the PGL-III-A for my 589nm.
The unique colors in the GLP hosts (473nm, 589nm, 593.5nm) are less expensive (most of the time), but the chance that they are VERY overspec is very small.
Hope this helps people a bit who are interested in joinging this CNI GB!