Kish's comments regarding her DD being a visually-motivated reader sound like my DS as he was starting to read. He seemed to go through a phase where symbolic decoding--be it car logos, corporate logos, letters, or numbers--was extremely intrinsically motivating. During that phase, he figured out how to decode CVC words and began reading simple picture books, like the Maisy books by Lucy Collins (so 1-2 short sentences per page), and he went on an arithmetic kick.
His interest in reading basically flat lined at that level for 2 years, and so I didn't push any progress beyond shared reading for fun and a few word games (with lots of word whacking!). It seemed like he felt satisfied and didn't see a need for more progress, because he didn't have the fluency or speed required for him to read books at interest level.
Almost 2 years ago, I began working with him with an OG system as part of our homeschooling, but found he didn't need direct instruction and could just progress through phonetically controlled readers. The OG system didn't last long, and he plowed through the books quickly. At that point, he could read more text-heavy picture books (e.g. Berenstain Bears, Franklin, Curious George) and simple chapter books (e.g. Mercy Watson, Magic Tree House). However, he still lacked the automaticity required to read at a pace and fluency that would allow him to simply read for pleasure. It was still "work".
For the last 6 months or so, DS has been comfortable reading pretty much any simple chapter book up to about a grade 3/4 level, and he can comfortably read a chapter or two at a time with changes in inflection for different characters. However, he's still not intrinsically motivated to pick up a book and read it independently in his head, so we alternate chapters aloud. I would classify the next stage of reading as being 100% independent, child-motivated silent reading. As DS is a very competitive child, I could see that happening sooner if he were placed in a mixed-age classroom with children a few years older than him.
In a nutshell, I'd say that many things count as "reading", but it's just a matter of the degree of automaticity, fluency, and intrinsic motivation of the child. The conventional reading steps probably apply to GT children, but some phases might be quite short-lived, occur much earlier than is typical, and phases might overlap.
