Terrance, I think there is a lot to be said for the Magnus Pump/Drive when all is said and done but it is really a question of whether or not the cost is worth it to you depending on your intended use for the car.
There 'are' numerous advantages. Although people's experiences seem to vary, Walbro pumps are notoriously noisy, the mechanically driven pump is by comparison pretty much silent from the cabin. The pump itself is bolted straight onto the drive which runs off the cam wheels. The pump is therefore accessible by popping the hood instead of going into the trunk, removing carpet, attacking an often rusty sender housing and stripping threads shearing bolts in the process etc. You won't need a fuel pump rewire. The pump shuts down as soon as the engine shuts down which has obvious safety potential at the track, and you are pretty much never going to run out of pump which means no further work down the road having people mock up twin Bosch 044s in tank etc. You can just run a -6AN line from the tank to the pump and another short line to the rail and pretty much be done.
The only real disadvantage I can think of is that of the cost, although I have wondered if starting the car would be any more difficult as I imagine you might need to turn the engine over a few times to get the system to prime but I really don't know for sure.
I think the deciding factor really is if a single in tank pump will meet your requirements. If it will, you might as well stay factory and just get yourself a nice clean non corroded sending unit. If however you find yourself exceeding the flow of something like a Supra TT pump you need to start weighing up the cost of fabricating various other options. Twin Bosch 044 in tank sending units in stainless steel will probably run you half the cost of the Magnus with the pumps. You'll probably need to do a rewire for that as well which doesn't have to be expensive but it's more money if you buy the kit etc. You will also discover if you start researching this that twin pump setups are not favoured by everyone as the pumps can fight each other if not setup correctly meaning you don't actually get double the flow as you might expect.
I have considered the Magnus pump fairly seriously but I am also very aware of the fact that a lot of people have made big numbers on single pump setups, so I very much doubt I really need that much pump for my rather modest goals. I do like the simplicity and reliability of mechanical pumps. There is a very good reason why OEM water pumps and oil pumps are mechanically driven despite causing parasitic power loss through the belts. BUT it's still a lot of money to spend for the reliability issue alone on what is in all honesty a non critical application and it would take a fair bit of time to pay for itself in that respect.
Edit: Just out of interest, are there any issues to running a mechanical fuel pump in as much as pressure rises with rpms? Can this be regulated by the FPR satisfactorily, and would you require a very large fuel return with a pump like this?