wyckyd,
Just to be "picky", OBD1 and OBD2 do not "stream" data. They are Request / Reply systems. The software requests the info, and then the controller returns it. This can be done many times in a row so it looks like it is "streaming".
One of the fundamental diff between 1 and 2 is that 2 was gov't mandated with certain data elements accesible in a standard way. Different OEM's implementation of OBD1 may have very similar data, but it wasn't mandated. So, each OBD1 vehicle will transmit it's own set of supported data. Also, the methods of connecting to the vehicle was OEM specific. So, there are fewer software / hardware tools out there for OBD1 because they were pretty much specific to the particular vehicle. Your 95 Blazer is supported by Ease Diagnostics scan tools (
www.obd2.com). But, a Jeep is not. They apparantly decided at the time to not incur the development expense for the Jeep. OBD2 is different - the standard method works with all standard (OBD2 complient) vehicles.
Enhanced data is yet again another story. Additional data is available, but in an OEM specific way. Connecting to controllers other than the engine controller is yet another can of worms - each module has got it's own method of access and unique data that is available which must then be transformed into people speak (degrees, rpm, mph, etc.).
CAN electrical architecture is the current tweek. Very few aftermarket scan tool companies currently support CAN due to it's newness and significant hardware and software changes from prior architectures. But, there is TONs of data available via this pipeline (faster too).