unichip is a better options than ssafcs, but classically, it was limited to 9 psi of boost and didnt have user control. if all you wanted was plug and play, the engine runs better and has more boost, unichip was great, but it was pretty expensive.. at least twice as much as a ssafc.
seems that has changed with the q series. baseline being under $300.
basically you can buy the q series with a plug and play harness that installs to your factory ecu plug. plugs into the stock ecu and the unichip. unichip will come preprogrammed for your car with a solid basemap, and if you want to modify the map, you buy the software, and plug it into your unichip via usb or bluetooth. somone can then ride with you while you drive and download all your unichip data points in real time, adjust, test ect all while you are driving.
as for the q vs q+ and q4.. i havent really found any details about it to compare. the biggest difference visible in the table would be drivers in the plus and q4. id GUESS those would allow them to run more injectors directly, ie if you wanted to run meth or nitrous, antilag ect.
im pretty sure for our needs the q would be just fine but im prob gonna get the q+ just in case. pope is prob being trained on this as we speak and will likely have a better answer.
basically it seems like a great compromise ecu. it can work in piggyback mode, not require modiciation of any of the cars wiring, pass smog ect, but has many of the features you would look for in a stand alone.
unlike the ssafc, it will help the car to run better in all conditions, not just in boost. i found my ssafc to have random stumbles and bogs.
at the $6-$700 they used to be, kidna expensive, but for $300, fk yea.