It's hard to understand what you are saying,
Generally;
The higher the pivot, the more feed-back you are going to get in the chain when you try to pedal through rough terrain. This is what is known as not "fully active". Any time you have a lot of extention going on with the swingarm, such as in a high single pivot, you have a lot of extention, this creates feedback and makes the suspension feel "harsh". This is especially annoying when you are trying to climb up a rough hill, because the suspension doesn't suck up the bumps and keep "traction", so you end up spinning out earlier and feeling the bumps a lot more.
The further the pivot is away from the chainline, whether it's high or low, the worse the pedaling is. This is a hard thing to balance though because no matter what, it's going to behave differently in different gears because the chainline can move between 3 rings up front (on most bikes). But generally, extremely high or low pivots are going to pedal pretty crappy.
Now, you may be asking about the overall length of the swingarm, like say for example a foes fly or fxr vrs a superlight or tituslocomoto, because the two latter bikes have a much "longer" swingarm. This does two things, one, it creates a different "arc" in the back, or travel path, although we are not talking a huge difference, and 2 it is going to be more flexy. The higher up you put the pivot, the more "rearward" the initial axle path is going to be, BUT you get into the negatives that I explained above, so it's a tradoff. It's also a matter of balance and how different manufacturers build their bikes. With foes they use SPV shocks pretty exclusively, so they have very low-pivots, without the SPV shocks they'd pedal pretty badly, but with them, they can be more active and have less extention than a bike that has a higher and more forward pivot. It's just different philosophys. A rearward axle path isn't the holy grail of suspension either, there are tradeoffs such as the extention that I mentioned above as well, so while it may work great on a big square hit because of the rear axle path, it will pedal like poop through a rough rocky section, or may be impossible to pedal through such a section. The "long" swingarms also create problems because they side-load the shocks more. If you look at some bikes lke the yeti AS-X, Foes Fly, and some Ventanas, you'll notice a "stiffening link" that is present. It doesn't really change the rate of the shock much (if at all on some bikes), but it adds a lot of stiffness to the swingarm and keeps it from "twisting", which puts side loads on shocks and shortens their lifespan. Frame-stiffness is another area where there are different approaches. With some bikes like santa-cruzes they simply try to beef up other areas to compensate, they can never be as stiff as a frame like a foes or yeti, but there's going to be more simplicity, lower cost, and less to go wrong with a design like they have. On the other hand, there are companies out there that believe frame-stiffness is a very top priority, turner with their bushing pivots, the foes that I've already mentioned, and so on.
There are a bunch of ways to do things. Some are not "wrong", just different. Some are better than others, but the cost begins to get out of hand, and even still, while they may offer real advantages, they may be only very slight.