Long time ago, I have used Dektol at 1:9 adding an ounce of acetone per batch. I don't think the amount of acetone is critical, particularly, because I believe that its function is to form sodium hydroxide from the sodium sulphite in the dektol, and whatever's left over doesn't seem to bother anything. If you feel the solution, it is very "soapy" meaning that it has become highly alkaline. I recall it's being quite a good developer, at least for sheet film, but since I haven't used it for a long time I can't give any particulars beyond what you've already read. I got this from Jack Welpott, in the mid 1960's. I think he got it from Don Ross.