The only concern I’d have with Genki for Text Fugu or Tae Kim users is that they all cover a lot of the same things (in terms of teaching grammar), and so likely wont get as much value for their money as a complete beginner would. The reading exercises were worth it for me though, especially in Genki 2. My reading comprehension was still very poor after TextFugu/Tae Kim, compared to now.

If you like that kind of structured practice reading, then you can also continue on into intermediate textbooks that work much the same way and continue building in difficulty. Not required of course, but very nice if you’re someone who learns better from that kind of method.

Michael, you’re probably better off just finishing Japanese for Busy People and then trying ‘An Integrated Approach to Intermediate Japanese’, which is the next step up from Genki 2 and often used by universities after the Genki books. Or better still in my opinion is ‘Tobira – Gateway to Advanced Japanese’, but you’ll likely have to import that from Japan (or maybe buy from whiterabbitpress).

I’ve not tried JFBP myself as Genki is generally said to be better by people who have tried both, but I imagine the content is probably similar. I’m sure you could find a sample of the first chapter or so of Integrated Approach to Intermediate and see whether it’s a good level for you.