There are two versions of TaskPaper that you can try:
Normal TaskPaper version are the "official" ones. TaskPaper previews give you early access to work in progress (sometimes known as bugs, other times know as cool features). You'll know that you are using a preview release because the application icon in the dock has "Prev" over it.
Anytime I do a build I actually build both versions. So they both have the same version number and code, just some some different config. So at times the most recent preview will match the most recent standard release. Then going forward the preview release will get some updates and again one of those updates (that's hopefully working well) is selected to be the new standard release.
If you decide to run the Preview version the software update feature will notify you of all preview releases that are made. If you run the standard version you'll only be notified about the standard releases that are made. The Mac App Store version will always just be the standard release.