I cannot produce direct quotes from any documents, but I have read that PAPI was produced for low vis ops. My last employer discouraged its use below 3-400 feet saying aiming point was the way to go, however when I was employed in the UK we used it and I continued to do so with anything else that was available.
If a smaller type is now using PAPI guidance solely, (ILS inoperative or not installed) does this mean that using the normal two reds and two whites will of necessity place that type higher over the threshold than desirable?
Yes if you consider touching down a little longer is not desirable, which would be the case on a short runway but not necessarily so on a long one.