The SLC has datalogging capability. I will log sensor input, but it cannot log actual ECU ouputs, like the fuel pulsewidth and what row and column the ECU is pulling data from in the timing and fuel tables. However, that is NOT to say that the SLC's datalogging is useless. It isn't. From what I have seen of the software, it is fairly capable of logging useful information that is outside the scope of the ECU. You can use the inputs to log things like EGT, accelerometer output, stuff like that.
ECUControl is a plug in to TurboEdit that logs data from the ECU (only) via the Hulog. ECUControl has very limited connectivity to outside sources of information. It is possible, but not easy or well supported or supported at all.
The Hulog cannot work without software on the other end. It is simply a translator. If there is nothing on the other end to request, store and interpret the data requested, it is useless on it's own end. It is more like a fuel line. It carries useful stuff from one end to another, but just by itself, it just sits there.
ECUControl, logging through the Hulog, will give you injector duty cycle, ignition timing output, MAP, RPM, speed, gear, barometric pressure, row and column data (very, very useful, IMO), logged AFR, IAT and ECT and calculated throttle position. I might have missed something. I stare at enough logs to know the important ones.
There is very limited knowledge on how to use additional inputs to log more useful stuff. The ECU is capable of it, as the PM8 ECUs for the CRX Hf have control of the EGR valve lift position via a valve lift sensor, which, if that could be harnessed would be boost control (if the ECU can respond fast enough, which we simply don't know). I know that Euro models of earlier cars did not have ELDs, and that input can be logged for a standard 0-5V input. I will be using that functionality in the future for other purposes, but, most of the time, I use it as it's intended function which is ELD compensation, as the OBD0 ECUs are pretty terrible at not running rich when there are higher electrical loads (lights, stereo, brake lights) on the system.
I haven't run Det cans . . . yet. However, a friend of mine has had very good success with electronic ones, better, in his opinion than the acoustic ones. However, ANYTHING is better than nothing. I can't get into more specifics than that on an open forum, however. If you'd like to know more, please feel free to email me. =)
The PGMFI forums are really like mini for gold. It's not nice and neat like a supermarket. You have to mine, putting in work. If you want to know about something, just email me and I can likely point you in the right direction or just answer the question right off.