I'm Cory Kolek, also a UI programmer here at Bioware Austin. I originally implemented the UI Customization feature, and I'm always looking for ways to improve it. I just finished adding the option to change the scale of your buffs and debuffs within the operation, party, player, and target frames. This change has recently entered testing, so look forward to it in a future Game Update!
Just want to say I really like the UI customization so far.. It's solid, easy to use, bug-free in my experience, and does its job well without any hassle.