Okay, first impressions.
Build: The ultraflex material from ListenHear is supposedly their hardest. The material is still "squishy", but it is tougher than the original molds I had. They might look acrylic, but they are not. The fit is nice and soft. I'll have to test longer wearing sessions, but they are very comfortable. The fit is perfect and the seal stays even when I try opening my mouth.
Sound: To start off, I love warm sound and bass that has impact. Because the body of the IE8s are not as flush to my ear, there is a bit less bass impact, even with the knob turned to max. I did gain what I would call texture. I am able to "feel" the music more now with the custom sleeves. It's a delightful feeling.
The sound is definitely extended compared to the stock IE8 tips. When I say extended, I mean a greater soundstage. The music now feels wider than before.
Isolation: The ultraflex material provides greater isolation than stock tips and also the EP material of my original order. The new molds also passed the wife test. I sat here watching her talk to me and I couldn't hear anything! She has already hit me over the head tonight when she was trying to get my attention. That definitely won't be the last.
So for first impressions, I'm definitely happy with more beneficial sound of having a custom sleeves. Compared to the pictures of the ACS molds, I think ListenHear could do a better job of integrating the IE8 body into the mold better. I feel the stick out too far from my ears when worn over the ear. Turning them upside down helps the looks a little, but not by much.
ListenHear's customer service is top notch. The original person with which I worked left for vacation, but was promptly picked up by a backup. Kudos to their group!