Not talking about issues with the function of a timing set, only that I see the small amount of slop in any chain causing fluctuations in the readings. I just don't think you can depend on the relationship between a camshaft and a crankshaft connected with a chain to remain consistent revolution after revolution, regardless of the quality of the chain. Makes sense if you want to know which half of the cycle you are on, but not if you want to know exactly where the crank is in it's revolution. Works great for an old school timing setup where it doesn't make much difference, but not in an EFI setup, in my opinion.
The front mounted crank sensor seems like a waste of time since the crank sensor works great as it is, if you want to use magnum on a-833, there is a 134 tooth flywheel with correct reluctor available and a magnum flex plate works on a 904/727.
I agree that the existing one works great, but up until a flywheel was introduced there was no option for keeping the 4 speed without going to a big 143T flywheel, and even now with your flywheel there is one big reason to want a front mount sensor - I already own a functional flywheel that is matched to my motor. Hard to see a good reason to spend money on something new, if I can find a way to get where I need to be without throwing away what I have. If I was starting over, or didn't already have what I do, then yes it makes complete sense to phone you up and ask for a price since I can't find it on your website :D (not a dig, just a comment). And maybe in the end it will makes sense to buy a new flywheel, but I don't plan on doing that until I have exhausted all my options.