Just got my BH6X extended battery. I put the extended door that came with it because the original battery door (for the BH5X) was a bit too snug for my liking.

I use a real simple silicon case - nothing fancy and very cheap (about $6 w/ $3 shipping at overstock.com - Motorola Droid X Premium Silicone Skin Case | Overstock.com). I was hoping that the extended battery WITH new door wouldn't cause a problem. I'm glad to report it works fine/VERY well. Highly recommend if you're a cheap bastard like me