Should I trade my soldier for the opponent's soldier in an otherwise piece-equal endgame?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Only if your soldier is genuinely doing less useful work than the one you would be removing. Two soldiers can look materially identical while being worth very different amounts in context, one blocked and going nowhere, the other close to a mating point or actively restricting the opponent, so the trade is not automatically neutral just because the piece count matches.
What makes soldiers unequal despite equal nominal value
A soldier stuck on the edge with nowhere useful to go contributes almost nothing; one near the enemy palace, tying down a defender or threatening to cover a mating point, is doing real work. Trading the useless one for the opponent's useful one is an excellent deal disguised as an even trade; the reverse is a mistake disguised the same way.
A quick way to check before offering the trade
Ask what each soldier is actually accomplishing in its current position, not just what it is nominally worth, in the same spirit as how material actually works in xiangqi. If yours is achieving more, decline; if theirs is achieving more, the trade is usually good for you.
Related questions
Does this apply to trading any pair of matching pieces, not just soldiers?
The same logic applies more broadly, but it is sharpest with soldiers because their nominal value is so low that positional differences dominate the comparison.
Is a soldier trade ever purely neutral?
When both soldiers are similarly placed and similarly advanced, yes, and in that case the trade genuinely does not matter much either way.
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