Gab, it sounds like you're hooked on the AFT with EMAX upgrade. Congradulations! "Why would anyone choose the 400 watt Xing vs the AFT 500 watt EMAX?" One huge reason- If you're fortunate like me, Xing's are installed free. Since I'm 50 miles away, lucky me. And there won't be any liability "out of sight/out of mind" distance problems. The Australia factor makes me a little nervous, kind of like the GNG China long distance variable. I mean, I do think the Global Economy sucks when it comes to parts and service. But don't listen to me. I've heard enough horror stories once the cash is deposited into their paypal account. Besides, why go 100 watts further into strangling your bike's power drive. Again, I've heard all the stories about crunched derailleurs and chains with high powered motors. I think it's called "taking a great idea (mid drive) and engaging it in overkill. Why do you think all the major manufacturers of mid drives keep it below 350 watts? 'Cause that's all you need for steep hills. Hey, I just want to do two 14 mile round trips a week, and get maximum range. But, to be fair, I'm sure both systems are comparable. I mean, Xing didn't start last week, and does have some history. And, finally, yes, again, the Xing is alot cooler looking.....period, and doesn't need an upgrade. To each his own and Good Luck, Joe.....