I prefer offset dots to top mounts. I first used a TA31 ECOS over 15 years ago and found it difficult to find the dot after breaking cheek weld as opposed to shifting the gun with my face still indexed to find an offset dot.
Having said that, the NX8 is perfectly usable for 90+% off applications. The dot is likely improving on the margins. I suspect that a dot on the ATACR is well into the realm of diminishing returns. However, I’ve not yet shoulder either the NX8 nor ATACR with a dot to test that theory. I just know that I plan to put an offset RDS on the NX8 first.