Your question is fraught with perils, but one point to make is that even though the time between major releases (e.g., 5.0 to 6.0) is very long in NetBSD, one can track the stable branch (e.g., netbsd-5) and update along it with amazingly close to zero nasty surprises. Thus you might not speedily get spiffy new features, but you'll be in very good shape for tracking security fixes.
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