>I get that it took a long time, But it will be a big project to bring what they have into the current version.

What incremental benefit would the end user get if they brought it up to the current version that would match the magnitude of the benefit they got by going to ASP.net?

They got a major benefit by this move.
The reason this app has survived since the CPM days (one of very few) is that the authors picked good inflection points and patiently waited for them.