I would agree that there is a strong visual component to early reading. I've found that quite a lot of NVLD students were first identified as reading disabled, but then "catch up" and even surpass in reading, but hit a wall in mathematics as they leave elementary (when math changes over from a vocabulary exercise (learning math facts--at least the way we teach it in North America) to an abstract reasoning task). The early years of reading instruction are focused on "learning to read", which is partly a symbolic exercise, much like higher math. Once fluency is attained, instruction switches over to "reading to learn", where reading is about language and communication, and now favors verbal learners.
I would agree that most GT kids with decent exposure to phonemic awareness activities will pick up reading on schedule or early. If there is a reading disability, it is likely to show up as subtler deficits in reading fluency and comprehension (secondary to fluency). Though, of course, classic dyslexia can still occur even in quite gifted children.
