Of course, it would be nice if we just get off our butts and do a full update for the early EVOs....
But until then, the 2G ECU swap is actually a very nice option specifically because it opens up more analog inputs for logging stuff like fuel pressure or oil temp or boost while running a MAF. It also lets you run the factory narrowband front O2 sensor for smooth closed loop option at idle and part throttle *and* log a wideband sensor on the rear O2 at the same time. I personally prefer this setup simply because you just can't beat the factory narrowband sensor at doing what it does.
To swap a 2G ECU, though, you're going to need to also run an external OBD2 adapter out of the ECU since the early EVOs use the older 12-pin style connector that's not only physically incompatible with the 2G cable but it's also electrically incompatible with the comm circuit inside the ECU.