I also like to apply reticles for downrange zeroing and rangefinding. IMO it's a good idea to completely understand the math behind reticles in 2nd and 1st focal plane scopes, and how to apply them.
We actually measured the size of a target at 1000 yds. to within .3" once using a mil reticle at a subtension other than std. milliradian (to obtain better accuracy). We had to mil a target of known dimension at a known range to calculate the subtension ("reverse milling") then remil the 1000 yd. target to calc. it's dimension. I have done this more than once successfully.
As it turns out the most basic form of the mil-ranging formula actually defines rangefinding with any reticle (and even turret) as well as downrange zeroing with reticles and/or turrets.
It's not often discussed but i agree that a backup system should be established in case the laser doesn't work.
The more you know about your optic the better off u will be in the field.
This optic system is a perfect example of that--
It's the Nikon Buckmasters 6-18x mil-dot on a 17 Fireball XP-100. It has been responsible for a few 1st shot connections as far out as right around 500 yds. in some light winds on prairie dogs. I apply the optic at 18x for rangefinding and windage reference where the mil becomes 66% of the 3.6 IPHY std. mil. subtension at 12x (12/18=.667, .667x3.6=2.4 IPHY). Elevation is IPHY with turret.
It is FUN to play with the math for long-range shooting...IMO!