I have an X5i on a 280 AI and it works fantastic. I have had no issues with it at all. I don't really like the extremely large knobs on it but as far as function, its been great. My grandson uses it mostly and he has taken animals cleanly out to 787 yards with it.
To be honest if your only going to 500 yards you could get a higher end Vortex Viper with dials as they work great as well. I had one and it worked for me for years with no issues. It did not have a good zero stop but what it had worked you just had to be a little more conscious of what you were doing. Not near as fancy but they do work. My hunting partner uses one on an 7STW and I have watched him kill animals for years with it out to 1000 yards.
To be honest if your only going to 500 yards you could get a higher end Vortex Viper with dials as they work great as well. I had one and it worked for me for years with no issues. It did not have a good zero stop but what it had worked you just had to be a little more conscious of what you were doing. Not near as fancy but they do work. My hunting partner uses one on an 7STW and I have watched him kill animals for years with it out to 1000 yards.