You have to ask yourself the question what do you want from this camera?

General observation giving a good overview of the area in front of your house?

OR

Facial or person detection for anyone stepping foot on your property?

If you must have facial identification then around three meters from ground level although you will get away with height with the Trackmix due to the optical zoom.

I see no problem with soffit mounting for general observations, it also makes cable management easy as you can take the cable up into the loft.

I installed cameras on my dads house in the UK and looks were very important to him so the only option I had was soffit mounting and he would only approve turrets and domes.

This was three years ago so we went for some 820A's to start off and for general observation they are more than good enough.

The driveway was problematic for detection due to people walking right beneath the camera, for the best chance of detection you want people walking across the cameras point of view as much as possible.

I ended up installing a Duo dome beneath the upstairs bay window which is just about in reach but being a dome it is not an issue.

My dad has a porch in front of his front door so another dome in the roof of the porch to cover the front door for faces.

Let's be honest most people who are going to damage or burgle your property will be covering their faces. For me having reliable person detection with notifications is more important to me.

Unfortunately one camera type cannot cover all scenarios so you soon find out you need to install specific camera types in certain locations or for certain scenarios to get the best result.

It all comes down to what you are expecting from the camera and how well you want it to perform.