A couple weeks ago I purchased a brand new p3 standard, got it home and the wifi module was defective, so I returned it and after reading that was a somewhat common problem and also a problem with range I decided on a Phantom 2 Vision+, so I ordered a used one from B&H. It was rated 8+, when I got it there was only one small nick on the side, looks like maybe a tip over or hard landing. The 2nd set of props hadn't even been opened and the battery only had 5 cycles on it. I charged everything up, hooked it to the pc and verified firmware was up to date, and when I checked it stated imu didn't need to be calibrated so I didn't do that. So, I took it out to fly and calibrated the compass. However, on the vision app, it is not showing the correct altitude. Sitting on the ground it is showing like -197ft...it doesn't fluctuate much maybe -197 to -197.5, very small increments. When I have it in the air it will hold position and altitude no problem, but the inaccurate height has me worried about the RTH should I ever have to use it. Should I go ahead and do an advanced imu calibration? I live in a valley in Tennessee, so maybe there is a huge difference from my residence to where it was originally calibrated? Also, mine is the v2 vision+, if I purchased a controller for the v3 with the gimbal dial, will that pair up with my quad and have a functioning gimbal dial?