I do not consider myself an expert on this. But I have been using a vehicle with 3CT engine and have used it to the max. It never failed me, during my travel to northern areas with a very nice fuel economy. But as you push this engine harder and harder on a 4x4 engaged, and heavy loads, it weakens up with time, and you need a service may be every three to four years.
But at a economy, this is the best bet you can have. I am using the same engine with CJ5, with rocky gearbox and it gives me around 10KM/Lit in town and 14 KM on highway... A bit noisy thou.