Based on my experience on an IDevice (I used a plain and simple Ipod touch) and a PC, I never noticed any advantages related to their clients. However, since both systems require a different set of fingers to play, I believe an advantage can be found when playing on a PC.

Obviously I am no scientist and did not conduct any professional experiments but one would think having at least six fingers on a keyboard (on both of my hands, I use my index, middle and ring finger but some people use their pinkies) would result to a faster reaction time than using two thumbs. With an Ipod, you constantly need to move your left hand thumb around the screen in order to move. Although this consumes the slightest amount of time, it still takes more time than having a fixed finger on an arrow key. This gives the PC user maybe a tenth of a second quicker reaction give or take over the the IDevice majority. Such an advantage is barely noticeable and all depends on the player.

I would say that's my two cents on the situation but the pennies are abolished in Canada.