Nice to see Best Buy carry these. Agree that this isn't exactly a "deal," but since so many people have had questions about these I thought I'd jump into the conversation. Not only do I own a couple of these, but I've done some development with them and I'm an expert in USB hardware. Apologies for the long post.
TL;DR: I think these devices are really cool, and I've personally gotten more than my money's worth out of them.
I discovered CronusMax a few months ago while looking for fight sticks for XBox One. I bought two of these devices and used one to play Mortal Kombat X with my XBox 360 MadCatz fight stick. Using it this way--for simple controller translation--is very simple and is pretty much plug-and-play.
The way CronusMax works is: you plug the CronusMax directly into your console, then plug a wired controller into the CronusMax. The wired controller contains an ID, which the CronusMax borrows. Once the CronusMax has the ID you can remove the wired controller and replace it with just about any other controller. There are some limitations on the wired controller you use to authenticate the CronusMax. I use a wired Microsoft controller for my 360 and a wireless Microsoft controller w/ play & charge kit for the One. 3rd party controllers may or may not work, and instruments like guitars do not. Just keep in mind you may need to pick up another controller to authenticate the CronusMax. It doesn't have to work--a used worn-out controller from GameStop would be fine.
The CronusMax itself is a mini computer that sits inbetween the controller and your console. It watches for inputs on the controller side, translates them, and then forwards the translated messages on to the console. At its most simple it does a direct translation (like PS-triangle button to XBox-Y button), but it is also possible to trigger pretty elaborate inputs to the console from simple controller inputs. For example, I wrote a program that loops through a series of movements to make Bejeweled 2 play Endless Mode for me. It's not terribly efficient, but it will run forever and will eventually complete Endless Mode while I'm sleeping, working, etc. As a test of how far I could take that concept, I wrote a few scripts for MK9 that I was able to use to automate complete matches, including fatalities for any character, using two controllers and two CronusMax devices.
There is a limitation with PS4 due to how that system authenticates controller. As others have mentioned, every 10 minutes or so there will be a brief interrupt while the CronusMax reauthenticates. I don't have a PS4, so I can't tell you how annoying that is (or isn't).
For keyboard and mouse I believe you need to have the CronusMax connected to a computer while you use the keyboard and mouse on your console. I haven't tried this because I'm a dinosaur who still uses a desktop that lives in a different room than my consoles. Apparently this can work quite well, but I believe it requires unique tuning per game. There seems to be decent support for major titles, and I didn't get the impression that it's terribly difficult to tune things yourself.
I don't know about tournament legality, but CronusMax supposedly offers a "tournament mode" that disables advanced scripts and uses only the built-in simple translation. This mode should let you use the controller of your choice on any system without allowing macros or other unfair advantages.
I haven't heard of CronusMax (or competitor devices) burning out USB ports, but it sounds unlikely to me. The USB controller (i.e., the console) supplies power to the USB network and controls all traffic. It seems more likely that a poorly defined Cronus device would burn itself out if it didn't handle the power supplied to it. If the device had a short, I believe the USB controller (again, the console) would detect that and shut down the port (kind of like a circuit breaker). Not saying it couldn't happen, but I haven't come across any complaints about that, and I haven't had issues with my CronusMax devices.
Re: CronusMax vs. TitanOne, there is drama and it is available online if you would like to search for it. My understanding of it is that the device inventor had a disagreement with the company he partnered with to launch the original device (Cronus), and he left to found his own company (Titan). He claims the device is his intellectual property. Cronus claims he was in breach of contract when he left and that the company has the rights to produce the device. Until there's a court case that decides who is right, do whatever research settles your personal feelings on the matter and pick a side, support both, or support neither. For the record, I am not affiliated with either company, but I discovered Cronus first and bought my devices before learning of the Titan. I've published some of my code with the Cronus site since I own their devices.
Apart from the drama, I believe the Titan supports one or two (inconsequential) programming commands that the Cronus does not. What this means is that anything written for Cronus ought to run fine on a Titan, but it is possible that some programs written for Titan will not run on Cronus. As the devices stand today, they offer nearly identical features; I couldn't recommend one over the other based on what they do.
That ought to about cover it. I'll try to stop by again to answer any other questions. I typically only check in here once a week or so.
