Hi, Earthworm.
If I understand you correctly, you are asking about the forward tilt of the dozer blade for pushing scrapers. It will make some slight differences whether the blade is tipped forward or back. The further back it is tilted, the higher up the blade the scraper push block will ride because the vertical point of the blade moldboard gets higher as the blade tilts back. This will have the effect of causing the blade to be carried closer to the ground which would make it slightly easier to get some of the weight of the back end of the scraper transferred to the tractor for traction.
This also makes it slightly easier to pick up a scraper on the run - IF you know what you are doing - without a bump, as the push block rides up the slightly flatter incline a little easier.
Conversely, the further forward the blade is tilted, the lower the point at which the moldboard face is vertical, the higher the blade will ride, the harder it is to get weight on the front of the tractor and the harder it is to pick up on the run with no bump.
Personally, I have never worried about changing the tilt of the blade from working dirt to pushing scrapers. I just worked out how to do it best without making any changes.
It is possible to pick up a scraper on the run, even without throttling back, if you know how but you can't do it with a full U-blade and it is very risky with an angle blade because of the danger of the corner tip spearing the rear tyre of the scraper. For this reason, I have only ever used a semi-U or straight blade in this way.
To do it, you appraoch the pushblock of the scraper at an angle of somewhere around 30 - 40 degrees (optimum) on a line that will bring the closer corner tip of the blade into contact with the near corner of the push block. The blade is carried with the cutting edge level with the bottom of the push block. Just as contact is made with the push block, you start to turn the tractor quite sharply to line it up behind the scraper and start SLOWLY lowering the blade, This results in a sliding contact with the push block and a gradually increasing force being applied to the push block, thus getting the scraper moving without shock.
It does take some practice, more for some than for others, but it does work. Most people initially find it easier to approach the scraper from the left to achieve this style of pick-up successfully but it can be done from either side and from varying angles, once you get the hang of it.
Hope this helps.
You have a wonderful day. Best wishes. Deas Plant.