I just finished up my megasquirt project.
I swapped my 1.7L D-Jet. The D-Jet is a pretty good system but I built a 2.0L and I had a hard time getting the parts for the 2.0L D-Jet system. The parts are out there just expensive. So I guess I based my decision to switch on cost.
I bought the kit from DIYautotune they did great. They shipped incredibly fast. I did all the assembly in a day. It took me a while to wire up the system. I used the stock temperature sensors. 2.0L injectors (I would probably not do that again the 1.7 injectors probably seem a better choice), LC1 wideband O2, and a TPS from a 98 Hyundai Accent. I used the in series resistors and did not use PWM.
The rest of the system is pretty much stock (ignition, etc).
It took me a bit to get it all wired up but it really was not that hard. I would say the engine rebuild was harder than the MS setup.
I am sure I will be tuning for weeks as the tweaks that can be done seem endless. But pretty much after 30 min of tuning I had a VE table that worked pretty well.
Bottom line I love the system!