What testing have you done that shows these blocks are made of shitty material? What material is the block made of specifically? I haven't had any thread problems yet and don't hear stories of tons of blocks failing in these cars.
Just wondering why you call these block inferior and what you consider "higher quality" blocks out there.
Keep in mind the intended goals of most Fiesta drivers.
1. Machinists, who work with blocks daily. Sleeving a block means removing material- during that process, guys who have experience machining different grades of metal get a good idea of the quality by the way the material behaves during the process.
2. For higher power levels we want higher clamping forces for head and main cradle. We use ARP style bolt+nut combination for that. As soon as sleeving and proper measuring is necessary, you need to tighten them a number of times. The original thread in the block starts to stretch due to extra force pulling it out and due to poor quality aluminium introduced for the block.
3. Distortion in the main crandle. Though I admit, this is also known to happen on other blocks. As you tighten the head with ARP bolts, the mains cradle is also affected. You may choose your color coded main bearings during assembly according to Ford's service manual, but as soon as you clamp down the head, the clearances will change- usual rule of thumb is that 1st and 5th will get tighter. If you are lucky, you will still have enough clearance to get away with this. If not, you will destroy the bearings/crank sooner or later and will start a painful process of diagnosing the reason. To do it correctly, main line boring/honing is necessary here.
4. Distortions in the cylinders. Same story, cylinders distort, when we clamp down the head. Different Ecoboost blocks have different results, but overall behaviour is still the same- 1st and 4th cylinder turn oval when clamping down the head. I have done testing and measuring only with dry ductile sleeves, but ductile is stronger and should even distort less than original. Again, if you are lucky, you will get away with this. What is more likely though, you will develop blow-by from the rings and this will develop into a long time problem. Going by the numbers, I measured 1,5 - 2 thou ovalness in 1st and 4th, this was enough to develop poor ring seal and develop blow-by.
Both last issues should be addressed by the machinist using correct procedures with torque plate. I will soon make an additional post to my build thread and cover this more thourougly.
As for which blocks to compare to- Subaru, Mitsubishi(4B11) and Honda for example. Blocks that engine machinists/builders work on daily and can give a good comparison against.