I've gone to Abelyne before. My hair is very fine and the Abelyne product would just snap off where it was connected. The problem is that they use pre-tipped hair that is a certain size/weight that was just too heavy for my hair. Will probably work if you have average/thick hair.
I also hated the hair quality. It was dry and tangled a lot -- even when they washed it. Maybe I just got a bad batch, because when I went back for them to look at it they seemed surprised by how poor the hair was.
I now use Ultima for Hair (also called Hair Xtend) in Vienna. This is great, but expensive. $1,200-$1,400 for 3/4 to a whole head. I went home for the Thanksgiving holiday and my Mom who hadn't seen me in a few months kept saying how glad she was I let my hair grow long like when I was young. She couldn't tell, even though we were togther all the time, went swimming together and she saw me combing it. I told her and she couldn't believe it. The hair was that good. The guy who does the extensions (Maurice), colors and cuts the hair to really match/blend it.
I've tried sewn in wefts too but it can't compare to the fusion. With fusion I can wear my hair anyway I want to -- in two or three braids, up in a bun, in a pony tail. And I can wash as often as i like.