1. On first question regards soundnes 15-18, the answer is - YES, this move is sounds and drawn. KingsRow discovered this some time ago. After 23-14 the drawn move is 11-16 and 11-15 loses.
2. On the second question ... this line is covered in Lee's Guide, where he gives only 11-15 and first few moves from winning path. I played this line two times with losing 11-15.
First time against R. Hallett in 1999 GAYP National and was close to win it.
Second time I played it against William Docherty in Eliminator match 2001 when I was 3 games down

However - I stopped playing it since then and I am unaware if there are any other takers of this line on serious occasion in modern days.
Personally I would not recommend anyone to use it today in tournament / match play against good opponents. Such experiments are good only first and one time

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The reason this line is popular in Internet play, because I started using it back to the end of 90's. After then it was passed to later generations from years to years !!!
Nothing new under the sun ! I was laughing when folks played this line on me recently on Kurnik.
Sincerely,
Alex