Ok I am back(was quite busy for a few days)..
The IFB-12(and 12A) at least when hooked to one of our machines, will only correctly display up to 540p if I remember correctly(it will not work at ALL with a 1270). I can say from personal experience that both 1080i and 720p would display resolution wise(looked nice), EXCEPT that the color of the overall image gets a very strong dark green tint to it. I have not seen a workaround for this issue yet...
My experience with HD-8 lenses was with the stock ALL PLASTIC versions found on 2nd generation 1272's and 1252's. The PT-65 and PT-43 lenses I have are both considerably sharper. Now there are HD-8 lenses out there(rare) that have aluminum housings and ALL GLASS lenses that I am sure are better.
For sake of saving myself some grief, and your thread some argument, I won't argue the color benefit with the 43's(look at a 1270 with its three different colored(plus coded to match the respective tubes) lenses). My take on the reason for this is that they seem to help richen overall image color quality. My local friends would also back me up on that one. Again, thats the last I will say of the 43's, I wont argue with other forum members here who disagree with me.