Yeah, I'm guessing that's probably why people aren't migrating. When there's no easy upgrade path and not a compelling enough gain, people will want to stick with the previous technology.
The LaTeX (declarative) approach is better. It's so much easier to write consistent, professional looking documents that way. The other (imperative) way is more like MS Word, and we all know how that turns out. Other declarative styles that are popular include markdown and html.
Is it easy to convert LaTeX to ConTeXt?