EE Cep comparison star variability
Looking at 38 nights of EE Cep single-visit coverage with coker30, star b is constant. The extremes of the photometry are 10.178 to 10.213 for V. (Remember, these values might have a 0.06mag or so offset, but I'm looking at variability.)
For star c, the extremes are 11.173 to 11.217 for V, again constant.
Any variation for these two stars is either in the hundredths of a magnitude range, or non-existent. The literature variation, based on photographic plates, was more like 0.2-0.6 magnitudes. That amount of variation does not match what I measure.
So I think these two stars are acceptable for comparison stars.