the logitech ones run on radio frequencies

  i have like 3 of em, 2 ball one optical

  if your a gamer, its a bad idea, 50hz refresh is not kewl.  i use mine on my laptops so its fine

  as for range, i havn't tried past 10-15 feet, theres no real point

  if i sit back from my 19" monitor even 6 feet i have trouble seeing text, so unless you have a massive projection screen i don't see the real point in sitting far away 

  plus the reciever base has a cord so its not limited to range from your cpu box.
as for the battery conservation, the newer ones i don't notice ems hutting down, the led varries in brightness all the time so its pretty fast.  
unless your bent on wasting batteries or squinting from afar your better off with something kewl like the corded dual optical logitech
