As I do not have a SAFC, I can only tell you about what the VAFC does.
It will allow you to set your VTEC engagement point. You can also set the fuel compensation for when you switch to the vtec lobe on the cam.
It will also allow you to make fuel corrections (+/-) anywhere in the RPM range. You have the ability to set your narrow/wide throttle positions. With those, you can also set your HI/LO cam profiles. So you basically have 4 positions you can tune at: Narrow/Lo, Narrow/Hi, Wide/Lo, Wide/Hi. I know that sounds really complicated at this point, but if you ever had some time in front of one you would understand it better.
Aside from the tuning, you also have 6 different things you can monitor. Intake pressure, throttle position, rpms, vteci (the incoming vtec signal to the ecu on/off), vteco (the outgoing vtec signal to the solenoid on/off), and correction (% fuel correction).
It will allow you to view up to 4 of these options at the same time in 3 different views. You can view them numerically, in graphical form (and record up to 20 seconds w/ playback), and you can view them as gauges (only 2).
It's actually not a bad toy if you ask me. Are there better options out there, sure. Is it worth the MSRP? I'd have to say hell no. I picked mine up off ebay 2 years ago for $200. Hope the info helped.