I've used the laser meters. They are much more accurate than the Robats and the laser meters can tare their zero reading which is a nice feature. I can easily see 1/8 degree changes or less with the laser meters.

Incidence really isn't measured from thrust line. It is measured from a datum, which is an arbitrary line the designer placed in the plans. It is common for thrust, wing or stab to be zero with respect to the datum, but not always. My point is don't assume engine thrust is at 0 degrees.

Probably the most important thing to remember about incidence it that it is has a dependent relationship with CG and stab incidence/trim. In other words, if you change wing incidence, it is similar to making CG and/or elevator trim changes.

Cheers