Well FWIW i actually swapped out my OEM MAF's for new VW ones (unbeknownst to me at the time) as they came up at a good price. I noticed no difference and LPH tests over a few weeks produced no differing numbers. I put it down at the time to my OE MAF's were still good, however, i was placated in the knowledge that i had changed them for piece of mind anyways.
I then found out that there were differences between OEM M5 MAF's and the VW ones, checked mine and found they were VW ones.
I ordered new proper Bosch 029's from Neighbour on here and replaced again. Again i noticed no difference but was once again, now 100% happy i'd put the right parts in. However, after about a week, i noticed pickup was a lot better and MAF tests showed an improvement in LPH consumption.