Yes, you can flash back and forth if you want. Just remember that the more you do "risky" flashes, the greater chance you have to brick it. I'm not saying doing it over and over again will eventually give you a brick, I'm just saying it's not your normal day-to-day flash, and it *is* the type of flash that can cause a brick if not done right. You're probably fine though since you know exactly what you're doing.
As far as wimax is concerned, I've heard that a bad radio flash can cause you to lose your keys. Seems to happen mostly with clockwork. As long as you have the correct backups, you should be fine. You'll want to verify before and after updating the wimax radio that you have your keys, the MAC address stays the same, and, of course, the version changes (up or down depending on what you flashed). The wimax_mtd command from the terminal emulator will give you the last two things (and probably won't work right if keys are missing, too). You need su to run that, of course.