Verdict
Built from the measurements below
- Accuracy is too close to call: LongCat 2.0 scored 48.8% and Solar Pro 4 45.0% on the same 80 questions, a gap within what chance alone could produce.
- Solar Pro 4 is 1.8× cheaper per question as billed ($0.0018 vs $0.0032), reasoning tokens included.
- Solar Pro 4 generates text 1.4× faster: 91 tokens per second against 67.
- Solar Pro 4 starts answering sooner: 0.6 s to the first token, against 1.4 s for LongCat 2.0.
- LongCat 2.0 accepts more context: 1M tokens against 524k.
Which should you choose?
Choose LongCat 2.0 for open weights you can run yourself and a 1M-token context window. Choose Solar Pro 4 for the lower cost per correct answer ($0.0041 against $0.0066), faster streaming and a quicker first token. The widest subject gap is in economics: LongCat 2.0 answered 7 of 9 correctly, Solar Pro 4 5 of 9. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap +3.7 points (z = 0.48). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.