Consistency is great - one of those products that as soon as you try it, you realise you've needed it all your life
I have both the Mac and the iPhone version, and wish that they could sync with each other. I know that you can copy data from one to the other using the WiFi web interface, but that is not the same as sync, nor is it automatic.
Here's a brief description of how I would ideally like it to work. I'm taking Things as my model, because I think it gets sync mostly right.
Whenever you open the Consistency app on the iPhone and you are on WiFi, and the desktop app is open on your Mac, it automatically syncs any changes between the two in the background, so that it does not interfere with whatever you opened Consistency to do. (Things gets this wrong as the sync window interrupts what you're doing and stops you from doing anything until it's completed.)
If you need to sync straight away, you should be able to tap a 'Sync Now' button, rather than having to close and reopen the app.
Another good model is Calengoo (Google Calendar iPhone client). Although the sync is automatic on startup, you can disable this and just hit the sync button whenever you need to sync. This would be a nice but not essential enhancement.
To my mind, the absolutely perfect model of sync is that between Simplenote and Notational Velocity (or any other Simplenote API client). Because it syncs via a web service, it works over the air (3G or WiFi), in the background, and with complete transparency. Once you've entered your Simplenote account details at both ends, you never have to think about or notice a syncing process ever again. This has the effect that whenever you go to your notes, they are always automagically up to date with whatever changes you made on the iPhone, the desktop, the web interface, or any other client.
I appreciate that multiple documents and contexts in Consistency make it not quite straightforward to determine what should be synced. I would suggest modifying the existing 'sync' screen on the iPhone so that you can manually upload or download a given context, and also check a box to 'automatically sync this context every time'. This screen would also show available contexts in the desktop version and make it possible to download these to the iPhone. The default should be to sync everything.