We currently have a number of desktop applications (PowerBuilder, Winforms, WPF) that make use of a single CHM for context sensitive help. We'd like to move away from CHM as it's difficult to maintain but we've not found a suitable alternative. Ideally we'd like our developers to keep the help files up to date (perhaps in a wiki) as they add functionality and simply export this to PDF or something like that, but is it possible to use a PDF for context sensitive help, or are there any other promising alternative to CHM?
If you are finding CHM files difficult to produce, you probably aren't using the right tool. I would strongly recommend you take a look at Help & Manual, which can produce help in all the common modern formats from a single source base.