I finally have one of these things in my living room. (just got it today, so haven't put it on) I've been driving around at 8psi for two months without one.

The first time I had my car dyno tuned (normally aspirated) when I got adj. cam gears and other mods.

The second time I got a dyno tune with the JRSC.

Both dyno tunes were well worth the money.

BUT, I'm looking forward to using the Safeguard to see if I can get good results. Quite awhile back I copied and saved this post of Larry's planning on seeing how well I can do to tune without being on a dyno. (see below)
here's post if anyone has any additional comments.
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"We use the device for a multitude of reasons. First we can be quite agressive with any tune-up, regardless of engine type.
There are never any two cylinders in any engine that actually "want" the same timing for optimum performance. With the SafeGuard, we can bump timing a couple degrees past what's optimum for the "average" cylinder and then allow each cylinder to "seek" it's individual timing requirement. So power production is as large a factor for using the unit as the protection aspect.
The fact that you can optimise every cylinder and keep all on the "edge" with the insurance that the engine's not going to be damaged, should there be a glitch in any of the many vital support systems, provides peace of mind and it also allows us to move all development programs much faster pace than we could without the device.
Once we've assembled a particular package, we'll adjust the timing curve so that the J&S is just "flikering" one light. Occasionally in areas where the timing curve might be too hot, we might see two or three lights flicker, but they will all go out, when the timing curve falls back inline.
My personal feelings are that using a J&S with it's dual monitor (or any A/F ratio meter) combined with a fuel pressure gauge inables me to find the "tune-up" that the engine wants within just a couple tests. When you're bumping too many lights, either pull some timing, add some fuel, or both. The fact that you can run to limits without smoking the engine permits one to achieve results fast and that's really something that helps out around here. As I've stated previously, using the equipment mentioned above, you can appear to be a tuning "genius" to others and even yourself.
NASCAR has made the J&S illegal, because we could tune and achieve almost 50 more horsepower with them. Having the ability to run a "qualifying tune-up" for 500 to 600 miles sure gives an advantage in the races and, although it might not be visable, having that additional juice to make a pass when nobody else can can sure help avoid accidents and it can also win races.
I wish they'd let everyone use them. Engine expenses would be cut in half."