These are Fancylugs' comments from the entry to the Bartali Roi des Grimpeur levers, which I include here as they are based on actual experience of using the Gloria lever and I think add significantly to our knowledge:

"The latter lever is the similar but not identical GLORIA lever. The latter were available through Ron Kitching (in GB) during the late 1950's and were sold with a rubber hood (all perished now, I have never seen one) are thus slightly later than the Bartali lever. Having used both types of lever for nigh-on 40years my prefered choice is GLORIA as they are more comfortable for my hands"

Comparing the R des G levers with this Gloria the latter is both simpler and more robustly made.  Whereas the former has two clamp bolts, the Gloria has just one and has a simple cast anchor point for the cable end while the former has a removable brass barrel.  The Gloria is slightly heavier, too.  The lever body of the Gloria is slightly less upswept at the end as well as being slightly longer, which differences, I think, explain how they feel more comfortable to Fancylugs.