I did build an EFI system using a '90 Dodge TBI and controlled by Megasquirt. I didn't have any beef with the hardware, although I wasn't using an IAC valve. It had great throttle response, vastly improved low end torque, and never gave me a moment's trouble.
With the TBI you get the fuel pressure regulator, injectors, throttle position sensor, throttle body, and some vacuum ports all in one package. My system was on a 360 V-8. Using TBI on the long slant manifold is another discussion, but that's not an inherent fault of the hardware.
Here's a look at that TBI/MS combo in action. A few days after I got it running and tuned, I drove it to Moab (about 600 miles one way) wheeled it, and drove it home. No problems. It liked the angles much better than a carb.
Fins 'n Things trail. Obstacles are steeper than they appear.
Oil pressure was going away here. Look closely at the tire tracks...
Throttle response helps here.
And here:
When dirt biker stop to watch, you got something happening.
The system being built and tested. This was my first Megasquirt build so I was all excited. Lou made me do it.
Comparison photo of the 360 TBI venturi size (L) compared to a Holley 2V carburetor for a 360. (R) This tells you something about EFI.
Mounted on the truck with a lot of wiring to do.
Here's my thread on RamchargerCentral documenting this build. I also did the TBI on the Offy manifold for the /6 which you can read about in this section.
RIP Ramus, you were a good truck. Lost in the great shop fire of 2009.