None, but the slacker seat angle is closer to a "standard" seat angle (73) than the original bike which was so steep, that he end up having to buy a seatpost with a huge amount of setback (40mm) and a new saddle that have a much longer rail than the original Brooks to be able to set it back even further.
When it come to fitting, you should always adjust the saddle position to the idea distance from the BB before figuring out the cockpit length.
None, but the slacker seat angle is closer to a "standard" seat angle (73) than the original bike which was so steep, that he end up having to buy a seatpost with a huge amount of setback (40mm) and a new saddle that have a much longer rail than the original Brooks to be able to set it back even further.
When it come to fitting, you should always adjust the saddle position to the idea distance from the BB before figuring out the cockpit length.