Claude Sonnet 4.6 vs R1 0528 for Persona Consistency

Persona Consistency demands that an AI maintain an assigned character across turns and resist injection attempts. Critical capabilities are: safety_calibration (refusing or correctly redirecting malicious or contradictory input), faithfulness (sticking to the provided persona and source constraints), long_context handling (keeping state across many tokens), and reliable structured_output when persona enforcement uses schemas or guardrails. In our testing both Claude Sonnet 4.6 and R1 0528 score 5/5 on the persona_consistency test, so the primary signal is a tie. To break ties we consider relevant proxy metrics from our 12‑test suite: Sonnet's safety_calibration is 5 vs R1's 4, both have faithfulness 5 and long_context 5, and structured_output is 4 for both. Also note R1 0528's documented quirks: it can return empty responses on structured_output and consumes reasoning tokens from the output budget on short tasks—behaviors that can undermine persona enforcement workflows. Our site ranks models by average benchmark score (12 tests, 1–5), and when scores tie, we refer to output cost and task‑relevant proxies to inform recommendations.

1. Adversarial roleplay with hostile prompts: Sonnet 4.6 is preferable — safety_calibration 5 vs R1 0528's 4 in our tests means Sonnet more reliably refuses or neutralizes injection while staying in character. Both models scored 5/5 on persona_consistency, but Sonnet's stronger safety metric reduces failure modes. 2) Long, multi‑session character arcs (30K+ tokens): both models have long_context 5 in our testing; Sonnet has a much larger context_window (1,000,000 tokens) vs R1 0528 (163,840), which helps when preserving earlier persona signals across huge histories. 3) Production chatbots with strict schema guards: both report structured_output 4, but R1 0528's quirk of returning empty responses on structured_output in our testing makes Sonnet the safer pick for schema‑enforced persona enforcement. 4) Cost‑sensitive deployments: R1 0528 is the practical choice when budget dominates — output_cost_per_mtok is 2.15 for R1 vs 15 for Sonnet in our data; both still hit 5/5 on persona_consistency, so R1 delivers similar persona fidelity at much lower run cost if you can tolerate its quirks.

For Persona Consistency, choose Claude Sonnet 4.6 if you prioritize robustness against injection, strict schema enforcement, and the highest safety calibration in our tests. Choose R1 0528 if you need a far cheaper 5/5 persona performer and can manage its structured_output quirks and reasoning‑token behavior.