yes there definatley is a user layer. it is accessed exactly the way you described. You set it up on the mixers menu utility-then user bank or the easiest way to do it is through the ttcontrol software again utility - user bank. Easy to do and works great to help give you exactly what you want.
One other thouht on flex groups...I actually use 2 of them as a stereo group and return my effects into them that way i have a stereo return in the flex group...just a thought.