Since I bought mine (ABZ) last year, I've been pretty much GAS-free (apart from the odd side-interest like an 8-string and a Fenderbird build with flats) for the first time in years. Sold the other higher end stuff, not missed them at all. It's the one bass I'd save from a fire. Love the tension of the 36.25" E, I have the P-Tone pickup fitted, love the tone with DR Low Riders fitted. I've tried the higher end ABI and ABII (had an ABI briefly) but they don't suit me any more than the ABZ does. The build quality is as good as anything I've played.
I had an issue with the P-Tone pickup I bought from Bass Direct, I posted on the Dingwall forum about it (I wasn't sure it was the pickup wasn't right or if it was me making a mistake) and Sheldon Dingwall responded the next day and dealt with the issue brilliantly. Excellent post-sales service, I can't speak highly enough about Dingwall.
They're not for everyone, but a visit to Mark at Bass Direct will be enough to tell you if they're for you - he has a large selection - it's a great day out!