I personally could not care that much about getting things "correct"
Part of my layout used Code 75 flatbottom using C&L templates as a guide. http://www.nmra.org.au/Layout_Tours/Solly/images/satjuly5_003.jpg
Later track work used Peco Code 100 Setrack for curves &Peco 75 flex & turnouts and some bullhead rail supplied by mistake. Once painted, ballasted & weathered, unless one gets down close, the variances are hardly noticed. The crew that operate on my layout are more concerned in that all works well than sleeper spacing, etc
As I see it, Peco is giving more choices.