I have a Predator and an X1 and have had many students using VR3 and VRx computers, all of whom agreed they are best described as a useless piece of sh*te by the end of their respective courses.
I think most of the comments above tell you how highly the VR range is regarded, basically, if someone tells you a VR3 is the best computer out there just stop listening and find better advice. Any computer which gets confused and say ‘Use Table’ if you miss a single deep stop is not good for anything except ditchable weight. The VR3 units and Inspiration rebreathers are something I can never figure out why anyone would want to use other than having already bought one and living in denial they basically bought a polished turd on a string.
For the Predator vs X1 issue I actually prefer the X1, it runs V-Planner live so is the same software I use to plan dives and also works on the VPM model which is far tend to be superior to the Buhlmann/GF models used in the standard Predator model (although a VPM upgrade is now available for the Predator/Petrel, I haven’t purchased this yet though!).
The X1 display is much easier to read, the Predator display is bigger, but can’t be read unless it is view straight on, the main screen seems highly reflective, while the X1 can be read from any angle making it much easier to see.
The X1 size is also much more compact, the Predator feels huge, although the Petrel sizes look a good middle ground. The interface in the X1 is superb, I find the predator menu’s very sluggish in comparison as you need to cycle back through menus is you press advance one time too many – the X1 is much easier to navigate.
The biggest down side of the X1 is probably the battery, it’s not replaceable and needs to be recharged. If you charge it it’ll have not problems at all as it has a long life and will normally last for several days of diving, but, if you forget for a week, then you can guess what happens. The X1 battery is practically bomb proof, although having just flooded my unit I may retract that, on the bright side it did still work even when flooded (but it did crackle when charging and the battery life was much shorter!) but it did still work. Credit to Liquivision though they are changing the battery right now with no problems what so ever.
The predator battery life is pretty good, although my unit seems to have a problem with battery warning signals whenever it gets cold (by tropical warm water standards) so I’m never sure what status the battery life is – the battery is only really used when it’s in dive mode which is when I get the warnings. I’ve probably changed the battery more often than I need to but as I generally use this unit as my main readings from a manual CCR head I don’t want it to fail suddenly for the sake of extending battery life.
If I had a choice between the X1 and a Predator I’d go for the X1 again, however I’d also be more than happy with a Predator too. If I had an option between a free brand new VR3 or a free used bottom timer and slate I’d seriously take the bottom timer and slate, the VR3 does make a good paper weight but also acts as a permanent reminder I bought the chocolate teapot of diving.