Blame my friend...Looking at EFI

I run the early version FAST XFI on my 400/496.

As a general comment, any system out there will handle altitude and temperature changes in stride since they use manifold absolute pressure as a key input. More altitude means less pressure and fueling gets adjusted accordingly. No fuss.

As another general comment, a fuel system that is reliable, quiet and lets you use full tank capacity takes some effort. EFI pumps do not like to "suck" much at all. Any meaningful restriction on the suction side can cause cavitation, noise and short pump life. Also, since there is no fuel stored in the carb bowl, even a very brief "uncovered pickup event" can cause lean or power loss. Robust systems I know of are 1) weld in sump in tank bottom with large and short (1/2" minimum) line feeding the external pump mounted low 2) In tank pump. There are options to convert a stock style tank or custom tank 3) External sump. The sump, around a quart in capacity, is fed by a low pressure carb pump with excess fuel returned to the main tank. The high pressure pump feeds from the sump by a short large line.

After the pump, 3/8" supply and 5/16" return should work fine. Before the pump, 3/8" is not enough.

I (now) use the in tank setup... after I had to come home on a flatbed once when the rail mounted pump/stock type pickup failed.

The in tank setup with FAST carried me on a 7 day >4,000 mile trip from IL to CA and back late last summer without issue. Cold start on the first freezing morning of the year at 7,000' in Flagstaff AZ. No problem. Later the same day crossing the desert at sea level and 95 F. No problem.

As far as the EFI sytstem itself goes, the newer stuff generally has a self learning fuel calibration. Enter your target A/F for various situations and it learns its own calibration. This should cut down tuning time a lot. On mine, all fuel calibrations are effectively user entered. Also I can say the FAST stuff seems well made and has been reliable with good tech support. I don't know the others.

Does the Edelbrock EFI support laptop tuning now? They used to use a hand held controller and weren't very "tunable" if you had anything with a little hair on it's chest.

I have a Holley 950 Commander Pro on mine and while it's stone age compared to what's out there now, it required a laptop to tune it and could be programmed to switch between different modes of operation.
I would at least want the option of laptop tuning on any system I chose.

It didn't much like my choice of camshaft and refused to idle clean closed loop but it could be set to run alpha N under 1800 rpm and problem solved.

I also found a free program that made the Holley system auto tune. It really helped me to fill in most of the craters in my fuel map but you had to monitor it pretty close because it would keep tuning it till it wouldn't run if you left it to it's own devices. It worked best if you picked a target a/f, drove around until you found the rough spot and turn it on until it was happy and turn it off. It usually took about 5 seconds for it to get right.

There was a company that used to make a TB that used port style injectors under the throttle blades that could flow lots of air and fuel but I can't remember who. I thought it was Promax but I went to their site and if they did they don't anymore.

Kevin