Personally and I am not the only one, I always TO/L in Atti. Often the GPS wants to move the MR a bit, I like being the only pilot when close to the ground or any object really. GPS does help in windy conditions, but even then I usually only use it while setting up a shot, when I actually fly the planned route I always fly in Atti, that way you have the feel of the wind. Of course I do this mostly for Video Production, but I do it for fun as well.
One thing you need to do is make sure the CG is in the middle and that you have the correct settings in Assistant for IMU/GPS placement. Check CG by lifting by the 2 diagonally opposing arms, it should balance level on both sets ready to fly with all Lipos etc on board. If you are nose heavy it will then to fly forward on takeoff. Move whatever you need to to balance, usually small adjustments to the Lipo is all you need to do. If you always fly nose heavy the front motors will work harder and wear out faster. You should check the temperature of your motors after landing, this will give early warning if you are starting to develop a problem.
Also I do a complete preflight check before takeoff including running the cyclic stick and checking that the motors are responding correctly (30-40% throttle is good for this) then I take off adding quite a bit of power up to 10-15' then I check that everything is good before commencing the flight. I like to be more like 30-50' up before switching to GPS. Often my Nazas and WKMs will wander 10-20' when GPS mode is first turned on. Usually later in the flight the accuracy gets better. And often GPS will hold my MR within 3-4", but not always.
Happy flying!
