Mark, the only guy I know of who's gone from HKS DLI to AEM CDI has had big problems getting it to work. THe DLI seems pretty routine to install and doesn't cause any issues apart from occasionally frying elderly ignition coils.
I think the "hot ticket" for widebands at the moment is the AEM gauge type unit, check it out on their webpage. Best place I found to buy was http://www.horsepowerfreaks.com, great prices, great service (even though mine hasn't arrived yet! - not their fault though, AEM's) and they do "package deals" which give you everything you need.
Going down the route of using the AEM for boost control via the GM solenoid seems very sensible, that way you can set it up so that if you start detonating, run lean, get too hot, whatever, you can cut the amount of boost you're running as one of the safety features. I'm flogging my Blitz DSBC and going this route.
I'm getting the AEM/Kavlico 3.5 bar MAP sensor (better than the GM MAP sensor apparently), GM IAT, GM boost solenoid, and all the connectors you need. One other thing to check is that there is a "battery offset table" available for your chosen injectors, this will save you a lot of hassle. Have a search in the forum or check out the injector wizard in the sample software to see if they're listed.