I got tired of all the ghosting on my 3.863, so I sent it in for a tune late last year. The tech at VR said they could not replicate the problem, but they upgraded the parts that are known to cause ghosting, and upgraded to 3.864. I get it back, still ghosts.
I was watching ebay for a while, and picked up 3.813, after calling VR to see if it was stolen. It was not, and I got it for a pretty good price. I was expecting the 3.813 not to work correctly, and I was correct, it was very slow to respond on K and X. Laser was fine though. I sent it in to VR for a tune up, and it came back one week ago.
I noticed that the 3.864 holds on to the K band signal 1.5 seconds longer than the 3.813, I assume that is true for all bands. This gives the illusion that the 3.864 is more sensitive, but that is not true. My 3.813 is as sensitive as my 3.864 with POP on detecting K band. The 3.813 is more sensitive on X band, by about ~100 feet, but that is based on X door openers. 3.813 falses on KA when I go up my driveway from the sat dish, just like the 3.864. Laser is very sensitive.
I am not sure when I will sell my 3.864, but I like the 3.813, and the arrows are a bit more accurate. I was really annoyed by the ghosting and band misidentificationon the 3.864.