Answer
For asynchronous version upgrades, ASCII .ma is the more reliable format for maintaining node graph integrity. Binary .mb is faster and smaller, but its opacity makes version-mismatch failures harder to detect and repair, and loss inside a file that does open can be silent.
Use .ma for any scene that must move between Maya releases or teams, and reserve .mb for performance-critical, same-version work only. If load time is a bottleneck, keep scene files light and use external caches such as Alembic for simulations instead of choosing .mb for portability.
Confirmed facts
- Maya compatibility is one-directional. Opening older scenes in a newer release is the supported path. Scenes saved in a newer release are not supported in older releases.
- .ma is a text script of createNode, setAttr and connectAttr commands. Unknown nodes appear as unknown, missing-plugin nodes are visible in the text, and a truncated file can often be repaired by removing bad lines.
- .mb is opaque. Truncation or version mismatch is usually unrecoverable, and problems that allow the file to open can be silent.
- .ma enables external audits: diffs, grep and automated checks can verify node counts, attributes and connections without opening Maya. .mb requires a Maya session to inspect anything.
Likely explanation, not verified
The precision concern for .ma is generally secondary. Maya writes floating point values as decimal text and round-trip fidelity is usually adequate, but behavior is version and attribute dependent. The risk is best validated on representative animation curves rather than assumed.
Save As to a prior version exists in Maya, but what it drops and how it handles new-version-only features varies by release. Unknown-node data retention when a plugin is later installed also varies by version and node type.
Steps for this case
- Normalize versions in a controlled step. Open the scene headlessly in the target version, run any upgrade conversion, and re-save in the canonical format rather than letting artists ad-hoc save across versions.
- Round-trip test on representative assets. Save the same asset as .ma and .mb, open in the target version, and script a comparison of node counts, connections and animCurve key values against a baseline.
- Forward-open test. Save a scene in the newer version in both formats and attempt to open it in the older release, logging errors and warnings per format.
One diagnostic detail that changes the recommendation: confirm the direction of your asynchronous upgrades. If artists on Maya 2022 must open scenes saved in Maya 2024, no format is truly supported in that direction. If the flow is only older to newer, .ma remains the safer choice.
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