I find the stock seat on my 1250 GS comfy for about 7-8 hours riding, whereas the one on my 1200 GS LC was only good for about half that.
I did have a low Sargent seat for a while, but found it too wide as the edges dug into my upper thigh and caused my sciatica to flare up. My missus found the pillion seat uncomfortable too
Same seats