I realized this thread is about the VPro vs. EMS while I decided to go with the iS which is effectively a "piggyback". Oh well, i'll continue to post here in case this can be helpful to someone else.
On top of the iS I'm using the sensor pack which is called the iF. The F-Con system (iS & VPro) can read from all the factory sensors but on the NSX there are some sensors not available from the Honda. Here's the initial setup i'm going with. I will add features as needed.
F-Con iS - Piggyback for OBD1 or OBD2
ECU Jumper Harness - Custom Built. HKS Japan doesn't sell a jumper harness specifically for the NSX.
Sensor Signals - If the factory ECU can display it, evidently the iS can read it. This is very exciting for me since I was not aware there was a "piggyback" unit aware of reading the native NSX OBD1 signal. These can be displayed via the 18 display (3 screens @ 6 sensor readouts for each screen displayed via composite video native from the iS; no CAMP unit needed). These include Engine rpm, Vehicle Speed, MAP output voltage, Throttle Position, Water Temperature, Intake Air Temperature, Battery Voltage, Injector Duration, Oil Pressure.
External Sensors - For other sensors the iF unit is needed. It's like a expansion pack for sensors. I'm using external sensors to pick up the following: Fuel Pressure, Oil Temp, Oil Pressure (because the OEM unit isn't great), EGT. I may upgrade to a more accurate IAT sensor and Boost/Vac pressure sensor to bypass OEM signals.
AF Knock Amp - This is HKS's version of a "UEGO" from what I can tell. The iS doesn't rely on widebands as mandatory inputs but it can be incorporated and I believe it has compensation tables if you have wideband O2s installed. I'm still looking into this but i've got them on order. Widebands aren't needed for daily operation but they are needed for tuning.
I will still have all my Zeitronix sensors running parallel for a while. This will help me figure out sensor calibrations and such. Pretty excited about everything.
p.s. the HKS hardware quality is top notch. I'm impressed with that so far...