According to the ResScan manual some of these extra graphs may be shown depending on the therapy device used but it doesn't list which devices those are. I am using an S9 AutoSet and am not seeing those graphs in ResScan. Although they're not important, I feel that SleepyHead provides more value at the cost of added complexity. I think a new user would probably be less intimidated by the ResScan display. Having said that, ResScan is a little more involved to set up initially.
One argument I can think of for having those extra graphs is maybe they can help to determine if there are Cheyne-Stokes respiration patterns. The flow graph is probably all you truly need for that, but being able to correlate the respiratory inhale/exhale times and volume of air in your lungs might be helpful. Maybe folks with certain conditions would appreciate the extra data.
One neat thing about ResScan is that you can get a summary with averages for any custom date range just by selecting the date range in the left column (mouse click & drag). SleepyHead offers averages for pre-defined buckets of "Last 7 Days," "Last 30 Days," "Last 6 Months," and "Last Year." Truth be told that's probably what most people will be interested in anyway.
SleepyHead is faster to load and access data. Hands down.
SleepyHead has a nice overview page with trend graphs that let you get a birds eye view of your detailed data over time.
I like that ResScan allows you to change your machine's settings right from the software. If you know how to change them directly on the machine though, the feature doesn't really add any value. Some people might find it helpful.
I think right now I'm leaning toward SleepyHead for my purposes, but I am reserved about committing 100% to either package because I still don't know which one provides the most accurate data analysis. They display slightly different numbers. Is it enough to be significant? I don't think so, but I don't know just how much delta there is. For all I know they both have equal amounts of error.
Below are screenshots from both ResScan (top) and SleepyHead (bottom) which show my summary data from the last 7 days. This highlights the numerical differences each of the software packages reports with SleepyHead giving slightly higher numbers.