I have had memories return recently, I feel they merely returned cause I was ready to handle those few memories. I didn't do any actual therapy with a T. However, I came to a point several years ago on this one issue....one specific abuse...where I had dealt with my feelings on what happened to me no matter who the abuser was. One of my alters let the cat out of the bag so to speak and It was hard to deal with and I did spiral through all my alters and created a new one...uggh...but now I am doing much better.
I had lost some sensation in my body due to abuse and now I can feel those parts of my body again which is great yet weird at same time. I can also eat a few foods I had associated with 2 of my abusers from early childhood...haven't been able to eat those items since I was 4yrs old.
I agree with amandalouise the memories come when you are ready. I don't know if therapy helps..but you need to be ready so you aren't floored when hit with the cosmic bat.
Personally, I prayed for years that God would reveal things to me when I was able to handle it.

Hope I helped a bit...

~AngelsRUs~