The ADL product, and some of the wx radar websites, overlay radar data (typically obtained from here) with sferics (typically obtained from here).
I would expect a stormscope to show the same thing as the sferics data and in general it corresponded fairly well, where I had an opportunity to compare the two in flight (not very often because at most altitudes I fly at where hazardous wx was relevant, I get no 3G/4G so would have been using Thuraya, which I don’t like because it often doesn’t work and is cumbersome to use, with the Thuraya satphone on the end of a USB cable) after allowing for the stormscope range being out by anything up to a factor of 2 (usually in the “safe” direction i.e. showing the strike a lot closer than it really is). Azimuth was usually very accurate (within a few degrees) relative to visually detected CBs; a lot more accurate than my £13k TCAS 
I found cases where the WX500 stormscope showed strikes (isolated ones, never a cluster of them) but the sferics image didn’t show anything, but never vice versa.
So I can’t agree that a stormscope is pointless, although I well see that Jason’s radar is better for tactical avoidance of hazardous wx if flying in IMC in a well de-iced aircraft – if the decision is to be either radar-only or stormscope-only. Big jets (a bigger version of Jason’s) evidently agree with this and while all have radar, most don’t have a stormscope or indeed any kind of airborne-delivered wx feed.
However the cost delta is a factor of 10 at least, and you cannot fit a radar to almost all SEPs, whereas you can fit a stormscope to just about anything. I think most twins used for serious IFR already have radar installed (not always working though, due to cost of repairs). You could fit a radar to a TB20 or an SR22 etc (an under-wing pod) and @pilot_dar will probably know how but the paperwork and flight testing would cost you a fortune
I have often used the stormscope to make long-range tactical decisions. In light GA IFR one is constantly making these, playing the buildup-avoidance game as far ahead as one can see; 100nm in some cases. ATC don’t always believe you (although that one didn’t involve the stormscope)
