True that, when it comes to performance cars it really is important to consider all those things. But this has a mere 105hp and a viscous center differential, which means almost all the power is sent to the front wheels under normal conditions so I doubt there'd be a lot more wear and tear vs. 141 when, say compared to a Subaru Impreza AWD vs. FWD, where the mechanism is significantly different and power is equally distributed. This merely supplies power to the rear wheels only if they're turning slower than the front wheels, ie. they are slipping so it's used to improve handling to a certain extent and only when limited traction is there. Slow to react and it tries corrective measures only after you're in trouble so not the smartest system, but does the job anyway. But FC will be affected adversely nevertheless as more weight and drivetrain components increasing friction are there. As for the TG review, the Audi got serious understeering issues due to front being too heavy and too much power being sent to the front, while the BMW is easier to control, especially for JC, due to it's oversteering ability. But all this is from assuming the 144 is similar to 114, as they hardly seem to 'evolve'.
As for the market, normal SL buyers would always reject 4WD cars IMO. And factory fuel claims for Japan in 10/15 mode is 19km/l for the 141 and 15km/l for the 144. So in SL conditions, I noted it's usually around 70% of that so estimating ~13km/l for 141 and ~10.5km/l for the 144.