I have recently purchased and received a new Axim 51v and I ordered a new case from Sena cases that I wanted to present my opinion about. I have never reviewed anything like this so I'm just going to tell you what I think.
I purchased the black leather case with clip from Sena, and so far I am VERY pleased with what I got. At first, I was a bit set back by the price as it seemed a little expensive. I had read several reviews of people that said they were worth it so I figured it was worth a shot. Two of the main things that I wanted in a case was to keep the profile of the Axim as close to "naked" as possible and to have a case that would allow me to flip the front back to a position that I would not have to fight with when using the screen. This case accomplishes both requirements for me. It adds very little to the size of the Axim and when you open the slim cover, you barely notice it is there when using the Axim controls.
Outside of these benefits, all buttons are easily accessible and there is even a hole that is perfectly placed for the soft reset button. Using the SYNC cradle is not a problem, it slides right in without having to remove the Axim from the case. It's also a VERY NICE looking case!!! I can understand the cost, the leather is top quality and the pieces are put together in a professional way. The coolest thing is in the cover. Instead of bulky snaps or clips, there are two magnets inserted into the cover to keep it down.
I got the clip feature because I plan to use the Axim often and would rather not have to dig it out of my pocket over and over. The nice thing about the case is that you can still use the case without the belt clip and carry it in your pocket without the clip attachment digging into your leg.
I am unsure of the protection level this case offers and I really don't plan to find out.

It seems to hold the Axim in a very secure position so I don't worry about it slipping out. I would imagine if it was dropped, the case would prevent scratches but I don't know what kind of protection it would give to the unit itself.
If you are looking for a case, check this one out and give it some consideration. I plan on getting a case with a little more protection for those times when I know I am going to put my little investment at risk. For everyday use around the office, this one seems like it is going to do just fine.
Thanks