I bought the bionic two weeks after it was released, I had it replaced 7 times by Verizon for many different reasons, at which point they sent me a maxx to replace the bionic. I was very happy with the maxx, didn't have any issues with it, until I sat on the screen and it cracked. I shipped my maxx to Motorola to have the screen fixed for 99 dollars, and after waiting for weeks for my maxx, Motorola sent me a maxx HD, because they somehow lost my phone. No big deal. Since I removed all of my personal info before I sent the phone off. Comparing all of these phones are easy. And since my wife still has her RAZR I can tell you first hand that the HD phones are far and above, better than the og RAZR. After the JB update on my maxx I would get 16-18 hours out of the battery, with this maxx HD I have been getting 26-28 with more use than maxx. The smoothness of the operating system is what the RAZR should feel like. And the larger HD screen when watching videos blows away the og RAZR. The phone itself is a Motorola, so it makes a call when I want it to. But the build quality of the HD is just superior to og RAZR family. The external speaker is too loud, I have to keep turning it down. But for me the most surprising part was the notification led, it literally scared me, it is huge. All of the little touches, from the circle widgets, to the notification counters on my email, and text, makes this phone that much nicer. But this is not just a small upgrade from the og maxx, its a completely different phone, that remains familiar. You really should just go and compare then side by side.
Hope that helps