I have the Tascam us-2400. It doesn't have ALL the bells and whistles that a MCU has but I got mine "b-stock" for $1200. Not bad for 24+1 motorized faders; solo, select, mute and a panner on each track; and a sturdy transport control.

You might want to check it out. 8)

I used the Mackie for a while and it was really pretty nice. Not as good as something like a Control 24, but I enjoyed using it. I just tend to be a little faster with the ol' keyboard and mouse right now.

What are some of the advantages to using a controller, and is it really worth paying $ 900 to 1500 on one?

It depends...if it improves your work flow then it is. I am so used to the mouse and keyboard that I sold my Mackie...although I have been considering getting one and making myself learn it. I think it would be faster in the long run. Right now I am using a Soundcraft Ghost which probably doesn't get used to the best of its abilities. I'm always using outboard pre's and mixing in the box it seems.

YOUR PRETTY MUCH PAYING FOR THE FEEL OF PHYSICALLY MIXING THEN.....NO REAL BENEFITS.....

I hear better with my eyes closed.
Due to room layout constraints my monitors (speakers) are behind me when I'm sitting at my DAW.

I'm considering a Mackie controller so I can sit facing my monitors, close my eyes, and mix without having to look at the computer screen - a handful of faders and a jog wheel.