I was going to say you should try a blackjack if you don't mind ditching S60.
I think you should just try out the E70...you can use it one handed if you want when the device isn't flipped open. If you have to compose a longer message, you can open it up and take your time. 2MP camera and wifi doesn't hurt its case either -
Now that you mention the N75, I think that would be a very good option for you...if it ever comes -