I have used an adapter, and I also have replaced a threaded setup with a threadless. My opinions on this - the threadless stem/adapter matched with the threaded headset just is too much.

Replacement with a threadless setup is better, but threadless stems with 1" steerers and skinny tubes still is not my favorite look.
It may have had something to do with the colors - IIRC my threaded headset was silver, but the stem was black. (I'm not sure on this.)

And I don't mind 1 1/8" threadless setups with larger tube frames. It's all in the proportions.

Here's a link to the 1" complete threadless setup on my skinny-tubed single speed. I don't think I have any picks with the adapter setup. Just didn't float my boat.