Simulating my Aircraft in SITL

I have a few questions about setting up my aircraft in SITL.

Firstly to what extent can I simulate my aircraft solely in SITL. Especially in regards to physical elements such as aircraft weight.

I have uploaded my parameters and adjusted some of them to work with the simulation. I can get it to fly but my current draw is super low. Should I just change variables such as BATT_AMP_PERVLT, my only hesitancy is that it will be inaccurate as these will then no longer be the parameters I use in my aircraft.

Similarly I am using the SERVO parameters from the working example simulation, but is there a way I can define these to work with my aircraft servo parameters?

In short, how accurate can I make the simulation of my aircraft before needing to introduce other software such as Gazebo?

See: Customizing SITL Multicopter Simulations: Tailoring Realism to Your Drone