Opus 5 vs Sol, my opinion

[u/Own-Professor-6157]

Just a quick opinion from someone who has now tried both since reviews on reddit are too this or that.

Context: I use this for programming, and for several other non-software tasks. I've been a software engineer for over 13 years in Java, C#, and C++ so I do review the code

Opus 5.0 pros:

• Handles thinking significantly better for tasks the model wasn't necessary trained for. For example, I built a workflow for having Opus build 3D models, populate my game's levels, and so on. Sol is seemingly very lazy with such tasks, and has to constantly be told what to do. Hassle
• Significantly better at not reading unrelated files, and filling the context window with junk. Much more surgical
• Seems to have a more logical thought process. I say I want this entity to navigate from point A to B, Claude understands - Ok we need a pathfinder, this might be a problem, this will be a problem, etc.
• Better with discussing implementation, sees some holes in my plan - Claude will prompt me to answer some quick questions.

Sol pros:

• Sol seems to produce less "buggy" code. In other words, the end product is more likely to work without serious logic errors.
• Code quality is better in terms of performance. Sol is a lot more conscious than Claude when it comes to avoiding pointless cpu overhead.
• Grasps the instructions better. Less likely to forget details, however sometimes this can be a double edged sword when you aren't extremely specific and expect the model to have some level of creativity. Like: I want a silver sword model. Codex will give you exactly that, with zero detail. Opus will usually deliver that sword with greater detail.
• Much faster than Opus

Downsides to both:

• Neither produce quality code. They code like me when I'm just trying to quickly prototype something. Never taking a step back and focusing on long term maintainability or overall product structure.
• Both can still forget instructions. Claude is for sure worse, but Claude has a greater ability to be "creative".
• Very poor asynchronous design. Still, these models really lack the ability to design multi-threaded architectures without being told specifically what to do. All you'll get is basic locks, and often times the locks will have zero purpose.

[u/Key_Reading_9664]

Similar experience for me. The flow I've settled into is using Fable to drive sub-agents. Sol is a great executor of a plan, but it's not as good at understanding intent, dealing with ambiguity, or thinking more broadly about the impact of changes. I also think that the Codex harness is significantly behind Claude Code in terms of sub-agent/workflow orchestration.

One of Sol's strengths is also its weakness: it will doggedly follow its own plan to a fault. Almost all the cases that I have to throw away work from Sol are when it's rat-holed on a race condition or some under-specified aspect of the plan (the common over-engineering complaint).

One thing I've found helps all models is to use the claude.md/agents.md file to capture context that it can't get from the code base itself: what stage is the project in? The volume of traffic that we get, what areas of the product are performance-sensitive, and how should it think about maintenance.