Choosing a New Java Phone

I may soon be in a position to buy a new phone. Assuming I stick with Cingular, what's the best phone for a Java ME developer?

I see phones listed with lots of nice APIs (JSR feature sets), but then I see it's all supposedly disabled by Cingular's security profiles. Are all the current phones locked down uniformly, or do I have options?

My old T616 lacked the socket protocol, but SMS and HTTP worked. My current S710a has socket protocol, but it's blocked from usage, as is SMS, so I lost Java's access to SMS in the deal. I fear my next phone will not allow session HTTP access, and make applications like Google Maps unusable.

I'm terrified to shell out money for a device and have it not be useful. I fully intend to use my trial period to figure out what works -- I may not even leave the store until I see some of these things work!

Cingular seems to like to tell you to just spend the "nominal" fees and get a certificate to sign your application, or have your marketing department contact them to build a relationship and get it signed by Cingular. I had also seen recommendation that an unsigned app should only be used for development and testing, but I doubt that's even possible, since an app won't function enough to even test it.

Do any of the phones allow installation of your own developer certificate? I know I couldn't on my Sony Ericssons.