Storing Persistent Data in Hybrid iPhone Webapps

I'm in the process of adding some persistence to a hybrid iPhone webapp. It looks like I'll be using the HTML5 Web Storage capability. I googled around and didn't find any comparisons of the alternatives or suggested best practices. Apple has a document called Safari Client-Side Storage and Offline Applications, which covers Key-Value storage and the JavaScript Database -- but makes no mention of hybrid applications.

It seems there are four possible options:

1. Web Database
2. Key-value storage
3. Cookies
4. Use a JavaScript to Cocoa bridge to access native persistence

I've given a little thought to the advantages and disadvantages of each (enough to decide to give HTML 5 Web storage a try.)  I'll update this document if I get any good feedback.


Web Database

Advantages

• Can be used in hybrid, online and offline webapps.
• Supported in iPhone OS 2.0 and later.
• SQL is familiar and powerful for those who know it and need it.

Disadvantages

• Use of SQL is overkill for simple persistence

Key-value Storage

Advantages

• Simple conceptual model than SQL
• Has both "session"and  "local"  modes

Disadvantages

• Only supported in iPhone 3.0 and later (although Apple isn't very clear on this)

Cookies

Advantages

• Tried and true web technology

Disadvantages

• Either not supported in Hybrid mode or requires extra Cocoa code to support.  (Does anybody have a definitive answer, details, or an example?)
• Extra data is transmitted to the server on each request
• Others?

Custom JavaScript to Cocoa Bridge Option

Advantages

• You can use any iPhone native mechanism for persistence

Disadvantages

• Requires custom Cocoa code
• JavaScript to Cocoa bridge options are fairly clunky
• Will not work for pure online/offline webapp