Yep by attaching to one side or the other your board will release better from the surf when being skull dragged as the board is on an angle also when you pull it back it it turns to you won way or another better for you to climb back on
The drag from either side when riding a left and right hander is also effected , as minimal as this may be to the mear mortal it does occur ,but it is the thickness / lenght of the associated rail webbing saver and actual legg rope that is most noticeable
A thick 10mm 10 foot leg with a thick webbing creates lots of drag hence i personally perfer the calf attachment to my leg for SUPen for a couple of reasons ,
the first being it means 3 plus foot of this think legrope is not dragging in the water when paddling and and dragging on a wave face
The the thick style webbing / rail saver is easier to hang on to when getting worked and rips less at your hand and fingers when controlling your board preferably when upside down
The recovery for your leg rope is easy to reach as you just reach down the side of your body to find it and retrieve your board also if you collect some weed around the leggie its easier to grab and flick off
Also i find kicking and swimming a bit less restrictive
Disadvantages is the paddle can get hooked up more often and some people hate the pull when getting skull dragged from the calf
The thin shorter leggie reduces drag significantly especially in small to medium surf , but often comes with a thinner rail saver that seems to rip harder at your hand and fingers when you want to use it for controlling your board.
Obviously they are not as strong .........so the size and power of the surf you use them in is more critical to have them not stretch out
They will spring your board back to you twice a quick for recovery being shorter
The other point is the length of your leg rope in comparison to the size of the board you are riding ............it should be a tad longer than the board you are riding , this gives you the ability to stay clear from it especially diving of the front to avoid your body(especially legs knees and ankles) being clipped by the nose and or having it spring back into your face
Call it over kill but im traveling with 4 including an ankle

finger safe supen and dont play with fireworks overseas