I have a Glamour and a SI trans am, which is similiar to (maybe the model before?) the SLR. Based on the websites, the current Glamour is about 60g lighter. You won't know which one your bum prefers until you try it, but I think of them as performance saddle vs comfort saddle.

The depression in the Glamour acts like a cutout but without the dampness in the wet! A good thing. I like the Glamour for shorter rides and especially if climbing; the upswept rear absolutely pins the sitbones to the saddle. Beautiful saddle. But the firmness also means the sit bones do get a bit sore on long days unless I'm out of the saddle every now and again (just have to remember).

But I think I will use the old leather SI for a tour, probably with gaffer tape under the cutout, cos there's never a problem with the sit bones day after day.