I'm more like you, but I like to have a physical button on my phone for the camera. I don't find the on-screen camera button user friendly, esp for half-press focus/exposure. It severely limits my choice of phone though...
Back in the day, PC gamers would learn quick repetitive sequences of key presses, sometimes with specific time delays. It would allow you to quickly select what you wanted so you could continue gaming in real time. I used phones the same way.
End, star, menu, up, select, up, up, select, "4390416046662023020548853052831,down,right,0225509680460,long 3,long 0", select, select, end, keylock.
I would send that text to my girlfriend while I was driving - while the phone was still in my pocket. It's impossible to do today with a smartphone. Luckily, dumb phones still have interfaces that respect certain rules of user input, and have simple single-tasking schedulers that obey your every command without hesitation. The only downside is the lack of good cameras, but the GPS nav and very minimal browsers give me almost all the functionality I need.
For reference, the best T9 texting phones i've ever used were Sony Ericsson. They were european-designed for a market that had long since embraced texting, and made it as natural, efficient and intuitive as possible. Oh the glory days...
[The text I sent above? "Hey i'm gonna be a little late, call you in 30"]
I had Sony Ericssons, Motorolas but the Nokia interface worked best for me (I had my Nokia N95 for a LONG time, 4 or 5 years). I found it came down to whatever you were used to, since the placement of the keys and combos were different (for things like commas, apostrophies etc) between the different brands.