What I want is one real-time (tactical) device and one strategic device.
Conditions dictate what might be acceptable.
Million-mile visibility out west, where one can see the cells far-off? Eyeballs alone might do.
Stuck in the soup (a layer) in IFR conditions with embedded storms? Stormscope and Nexrad.
In and out of clouds with some cells building nearby? Nexrad + Stormscope+ eyeballs.
Below the layer or above the layer with decent vis? Nexrad + eyeballs
In some places on IFR you can't get the altitude to see everything you need to see. DC area is one, Chicago is another. In others you might be in a layer (Gulf coast is notorious). If you can't see them build, you want a tool that can help - IMHO, for the way I fly, Nexrad is very useful, but not the whole story.
If you can see it, fine. I got a similar call out of ABQ a few years ago - by the time I got halfway to the hole, it closed. I could see that one, easy enough to go around. But plenty of times on the DP out of Washington area you're altitude restricted and simply don't have the option to see more than a few miles (if that much).
It depends on your flying. Every tool expands the range of conditions - I agree. nothing<stormscope<Nexrad<Stormscope+Nexrad<onboard radar+Nexrad. Each device expands the range of conditions, but none is perfect. I fly a fair amount of conditions that include embedded - the eye is not sufficient w/Nexrad (for me).
Comparing my flying in NC with flying in and out of the DC area, I realize that I'm a bit spoiled by dominant Bermuda high conditions. Given that operations to and from one's home base shade one's perspective, my home base is often under Bermuda high conditions where blue skies regularly turn into afternoon TRSAs. Usually with high bases, big buildups but with some separation between cells. Moving 200 miles north, summer conditions lean more towards milky skies, lower ceilings and obscured buildups.
I also fly out of the sticks. So departure/arrival procedures and the altitude restricted clearances common in the DC/Phillie/NY axis are limited to certain destinations rather than my home base. Being cleared to fly over the Class Ds and under the Class Bs around NJ on a milky convective afternoon gets pretty hairy though the main hazard is often aluminum.
So I can see how a Stormscope can give you something more than eyes and Nexrad though a powerful radar unit would be ideal. Without sferics or radar, there are some limitations that this pilot has to respect. A Stormscope would clearly add some capability to Nexrad, ground radar and a well calibrated pair of eyeballs.
Faced with outfitting a plane for IFR weather flying, especially if doing it from scratch, Nexrad is clearly the first tool. Given the cost:benefit ratio it would seem almost mandatory for the OP's situation. As I recall, he didn't have it and could have used it, though it was a flight from a year ago and I'm sure he's added it since.
For me, Nexrad has made IFR operations in the SE summer more of a hit than a miss proposition. Heck, it makes VFR operations less of hit or miss proposition too but it can also get you in deeper in trouble. I'll probably go no further given what's out there. Radar remains out of reach and sferics costs a bit much for the added capability in my flying.
When I was deeply involved in developing my panel I was unaware of any fellow builders putting sferic devices in their planes. I didn't see any support for it in the experimental EFISs either. Not sure of the reason except that the calculus for many was probably similar to mine. If I had it in an existing plane, clearly I would want to keep it.
Even radar has its limits as I guess all users know. Just after the G396 with XM came out, I had it in my Maule for frequent trips to south FL. Coming up the coast to a convective mess around Jacksonville I was trying to figure out how to get inland of the coastal line of convection. To the eye it looked like a solid wall. Jacksonville seemed to be totally blocked off and I was faced with heading out over the ocean (noooooo) or doing a 180. However, I could see a hole right over the city on Nexrad. Some jets coming down from the north were apparently painting cells that seemed to completely block them off from JAX airport. Coming from the south, I could 'see' just enough with Nexrad and the mark20s to ask for vectors right over the airport and the city. At least one of the jets went for an alternate as I was flying over the airport with visual contact. I know that the G396 quickly found its way into a lot of pro cockpits but it had only been on the market a few months at that point and for a moment, me and my Maule had the advantage! It was very cool.
Now if the little airport I finally landed at had had some SS Low Lead, my little victory celebration would have been more sweet.
