To my eye, continental splinters do run longer than on English guns. Compare this to many London guns posted on the photos section to see what I mean.

They also tend to run in parallel with the barrels for a longer distance before cutting inward at the end (looking from the bottom). English splinters tend to taper up to the barrels quicker owing to their shorter length.

I had a Genossenschaft double with a forend like this Heym, and I must confess it did feel good compared to my English guns. I guess I tend to run my left hand further out when shooting offhand, so with my Greener for instance, I usually have quite a bit of barrel in my left.