Jeff,
I have had first (and still do) Blitz and secondly came on with TOA this spring.
While they both watch for strikes, they offer vastly different information, despite thinking that they'd both see and report strikes.
Having some relatively 'local' storms move by I see that both systems fail to report known strikes, it is the nature of the beast the way they are designed and the software that has to be satisfied
While TOA gives nice zoomable displays, and makes an estimate of the current for CG strikes, the Blitz system gives you far more control over what you see, with lightningmaps.org and the individual controller being able to send you much more info than TOA gives you.
Unless you have a major financial bind, I'd keep both to try. I'd be hard pressed to give up one or the other, although I'd probably hang on to the Blitz if pushed, just becasue it gives me so much more info than just strikes on a map.
PS, I wonder if it hasn't been sold you might say what your minimum, non-insulting, price would be and let it bid up from there? I doubt most people would have any idea what the equipment, plus some for assembly, cost you.
Good luck! Dale