I would equate my Futur on 1½-2 to my Ikon S3S and my Gillette Super Adjustable on around 6 to 7, so yes it is pretty aggressive but manageable.
IMPORTANT: DISASSEMBLE YOUR FUTUR REGULARLY TO CLEAN ITS MECHANISM.
I received today from Merkur, the replacement head top cap to replace my very corroded one. They very kindly sent me this free of charge, in spite of the razor being out of warranty and bought second hand. They also included a replacement razor blade platform as well. I found a video here www.youtube.com/watch?v=GuDCHb9-uJ4 showing how to disassemble the Futur. When I got it apart - yerchhhh! Obviously the previous owner had never taken it apart or cleaned it properly. Corrosion, fungus, soap scum and hard water crust. I cleaned everything up with shower cleaner and an old toothbrush and then lubricated it all with silicone grease containing micronised teflon (wonderful stuff available in Europe from RS components and in the US from Radio Shack). It now adjusts very smoothly and goes below 1. Before it would only go down to about 1.25 before it went solid with a horrible squeak. I think it should probably be taken apart about once every two months or so, to clean thoroughly to prevent a reoccurrence.
Gillette S. Adj, Stahly Live Blade, Feather AS-D1, Eclipse RR, and Ikon S3S