Manifold - Plastic or Alloy - Which is best

Some people say the Octavia had both plastic and alloy manifold and I've been wondering why. One person dealing in engines in Oldham told me they changed back to alloy manifold on 2012/2013 engines but I'm quite puzzled about that and not sure if that is true. I am surprised about these changes and would have thought the changes would only be for the purpose of reducing costs. a plastic manifold is clearly much less expensive for the company and more likely to fail during vehicle lifetime - creating extra revenue for VAG - often extremely expensive replacement for many owners who have become frustrated over the years about manifold flap failure. It appears its not failure of the flaps themselves but the mechanism in which the metal pivot rotates and allows the flaps to be over rotated to a point where an error is triggered. Its really an unnecessary error - there could be more leeway. It shouldn't be necessary to instruct the ECU to turn off the flap motor and illuminate the EML at this very small over rotation that is perfectly recoverable. I've looked at this situation a long time, first in an effort to fix my own problem. I was reluctant to buy a new manifold but I did so eventually, with a motor. I noticed the motor did not command any movement in the flap. When I removed the end cap to the motor housing, I saw that it was not capable of working because the internals were not of a kind that could determine the rotation position of the flaps. Eventually I traced my problem (open circuit or short to ground) to the fact that the motor body inside the housing was shorting to ground for unexpected or unknown reason, but after insulating the small 12v motor, I regained functionality and was able to use my original flap motor the V120 by VDO. The Chinese motor I purchased was of no use. It was not possible to strip it down and use the new parts.

The best solution for failure of the plastic manifold motor / over rotation is probably to use the manifold repair bracket. But bear in mind that if it is for the plastic manifold you must get the specific repair bracket part for that manifold. Also removing the manifold motor or screws sufficiently to install the bracket. There is a tiny Wurth ratchet that will enable a dextrous person to tackle it, however you would need to cut a T27 bit down to the shortest possible length you can drive with the ratchet. That means you will probably end up shortening the bit by 50%.

I am however interested in SKODA/VAG's approach to this problem and was informed that the Octavia amongst others was later fitted with a metal manifold once again. Has anyone here got any info or history about the different manifolds that have been used and during which periods? Was an alloy manifold still sometimes used on MK2 cars after 2012?