I think students MUST NOT learn kana-ony version of japanese. This statement is easy to prove. You may like to conduct a following simple experiment:
- First, find a native Japanese friend,
- Set a trap for him or her: Go to coffee place together and chat;
- Ask your friend to explain any japanese phrase to you.
- Suddenly, while him or her is confident and relaxed, ask to write the phrase in kana only.
- Write something yourself in romaji or kana and ask your friend to read and understand it.
- Repeat 3 to 5.
I've got a strong feeling that reading Japanese texts in kana is more difficult than reading "normal" Japanese texts. I think this is true for foreign students as well. But at one condition: you must know the kanji that's in use it the text you read.
My current reading process can be debugged like this:
- I look at the text;
- I visually recognize kanji in the text;
- If I know the kanji meaning it helps a lot allowing me to bypass "internal reading" stage, "internal hearing recognition" stage and "translation" stage". Of course it's for the kanji part only. But it saves a lot of brain power and it's fast!
- Often, I know the phrase's meaning before I actually read it. In many cases I don't remember kanji phonetic reading but know what the kanji means;
- After recognizing the kanji inclusions, I look at the surrounding kana to find endings and particles;
- Japanese sentence grammar structure looks much more logical to me when I see words in their true kanji form.
My conclusion is following:
- romaji is a useful invention, let it live.
- kana-only student books must be destroyed!