Should you rebuild an aging, smoky two-stroke or upgrade to a four-stroke?

[Tyler_S]

I recently purchased a used 18-foot aluminum fishing boat that came with a 15-year-old two-stroke outboard motor, and while it starts and runs, it's clearly underpowered and smoky. I'm trying to decide between investing in a comprehensive rebuild of this older motor or biting the bullet and financing a new four-stroke model, but I'm unsure of the true long-term value. For experienced boat owners, what factors tipped the scale for you when deciding to repower? I'm particularly interested in real-world fuel efficiency comparisons between modern two-strokes and four-strokes of similar horsepower, the reliability and maintenance differences over a five-year period, and whether the increased weight of a four-stroke significantly affects the performance and handling of a lighter boat like mine.