When deciding between streaming and buffering for handling network requests, especially in environments like Cloudflare Workers, there are several practical limits and considerations to keep in mind. The choice between streaming and buffering often depends on the size of the data, the network conditions, and the specific use case. Here's a summary of the key considerations:

Streaming

1. Best for Large Data: Ideal for large files or data streams where buffering the entire content in memory is impractical or could lead to high memory usage.
2. Real-time Data: Useful for real-time data transmission like live video or audio streaming.
3. Slow Network Adaptability: Performs better under slow network conditions as it begins processing data as soon as it starts receiving, reducing wait times.
4. Back Pressure Management: Allows for back pressure handling, which is essential when the rate of data generation is faster than the rate at which it can be consumed or transmitted.

Buffering

1. Ideal for Small Data: More efficient for small files or data where the overhead of setting up a stream is not justified.
2. Lower Complexity: Easier to implement and understand than streaming, as it involves simple read/write operations.
3. Memory Usage: Can lead to high memory usage for large files, as it requires the entire data to be loaded into memory.
4. Fast Network Optimization: Works well in fast network conditions, where the delay of loading the entire file into memory is minimal.

Crossover Threshold Estimation

The crossover threshold - the point at which streaming becomes more efficient than buffering - depends on several factors:

1. File Size: Generally, files larger than a few megabytes (MB) are better streamed. For smaller files, the overhead of streaming might not be worth it.
2. Network Speed: For slower networks, streaming can start providing data sooner, which can be crucial for user experience.
3. Memory Constraints: In environments with limited memory (like Cloudflare Workers), streaming can be more practical even for moderately sized files.
4. Client Capabilities: The ability of the client to handle streamed data versus a complete buffered file.

As an estimate, the crossover threshold could be around a few MBs (e.g., 5-10 MB) for most use cases. However, this threshold is not fixed and can vary based on the specific requirements and constraints of your application.

In summary, choose buffering for small data sizes and fast networks, and prefer streaming for larger data sizes, real-time requirements, or when working under memory constraints or slow network conditions.