I certainly and definitively agree with @legotownlinz: Most 'regular' LEGO people I can think of (aka the every day LEGO fan who has a small hobby and thus tight budget) own the standard PF R40 curves yet. If you want to expand your train layout and build an outer circle, the first thing you'd buy is the next bigger radius: R56.
No question, you could and will have fun with larger radii as well, especially at 'professional' exhibitions or at your LUG, but the logical next step is –imho– the R56. You can realise parallel tracks with R40 easily and run your trains along them, which is going to look very appealing :-) And not to forget the 'better halves' who are more likely to accept the smaller footprint as well
I am very happy and thankful for your hard work @coaster and I hope we will see many many more great (molded) train products from you! They seem to appear fantastic and I'm looking forward to buy at least four PF R56 circles this year. Btw, do you already have a rough time schedule or some kind of product roadmap for 2018? Am visiting your website at least on a weekly basis
P.S.: And many thanks again for your generous promotion over at FB