maybe question is comparing carbs vs fi, but original zenith carbs vs original fi
i mean of course you can install other carbs, or other fi system,
but if we would like to compare properly those systems they need to be the original ones
my opinion, zenith carbs are a very nice system, bits are simple, they involve easy manual operations, there are still enough spare parts to replace and fix them, preowned carbs can provide you with spares, and dealing with them is simple, but there are few experts around to do the job, if you can fix and fine tune them it is a very good choice
djet fi is a much more complex system in comparison, ecu, injectors, a couple of NLA valves, and the air regulator, all those are NLA, difficult to fix almost impossible, fine tuning involve the use of a dedicated bosch equipment, very expensive
probably i have to add that i have no idea of how to deal with fi, and i can do carbs, on the other hand there are more mechanics that know about fi, but this is also tricky, as they are taught in modern fi systems and they might get stuck with djet
i would never buy a csi myself, i consider the original system will be more difficult to keep than keeping the zeniths
if you are not for originality, there are no worries, you can always install an e30 efi, a chevy motor, or even a tesla laundromat motor and the coupe will move