Or it may have to do with the fact that I was wiring a 2003 CBR 600 F4i instead.
The GReddy emanage system does provide a bit of assistance, since your stock ECU is still in place. Assuming all the dip switch settings are correct for the vehicle, the universal units and harnesses will build a base tune utilizing the tune currently in your ECU. Using a Wideband o2 setup will provide additional assistance, as the piggyback will build a base (slightly fuel rich) tune from which the vehicle may be further tuned.
AEM has released their F/IC (Fuel and Ignition Controller) and is currently developing "plug and play" harnesses for the product, however they are initially focusing on the Honda K and B series engines, and a few select Nissan engines. I wouldn't count on a harness for the Crossfire being available soon. Additionally, the F/IC does not support a target A/F ration tune or any tuning assistance. As with the eManage, the vehicle will start using the base tune within the ECU, but the AEM unit, you will need to perform all the tuning.
Concerning the DIY mechanic: these units walk a fine line. While they are targeting the tuning market, it is more involved than a basic bolt on (which of course you are already aware!) With a basic understanding of vehicle dynamics AND wiring system, it is manageable. With your knowledge you should be more than capable of performing the install. The install will require you to splice your Map/Maf, injector, ignition and other signals with the piggyback harness.
With a lot of patience and logging the systems can provide a significant improvement over stock conditions, especially in hard driving situations (i.e. high RPMs and Load.) The vehicle will begin to remove a significant amount of fuel and retard the timing in such situations with an KR (knock) signals. This is very common on stock vehicle. I know the GTO in particular is very sensitive to and knock and will during logging I have seen the ECU significantly retard the timing during such situations. By tuning the vehicle as close to the edge as possible, but avoiding knock you will see a marked improvement in the consistency and performance of the vehicle.
With a new daily driver and FSAE in a lull, the Talon project car should have an eManage system installed soon, I will be sure to post progress, results, etc of the project as it progresses.