this is more or less consistent with everything I've read on the topic, but X can be a surprisingly long distance (billions of km under thrust, or millions of k

this is more or less consistent with everything I've read on the topic, but X can be a surprisingly long distance (billions of km under thrust, or millions of km in "cold running" mode). you would be detectable from pretty much anywhere in the solar system while burning, and still quite a long way away in "stealth mode". even if you had really effective stealth in cold mode, adversaries that observed you while burning could accurately predict your trajectory. X+1 detection range isn't much of an advantage if X already includes most of the places you can actually be and/or X is already an order of magnitude past effective weapons range.