My Mason roadie is steel and so is my Stanton MTB. So 90% of my ultra events are done riding steel bikes these days. I rode the Tripster during Seven Serpents and any other events and I've been fanging around on my old Focus CX bike since the Tripster went to Poland.
Almost 4k for their Di2 carbon jobbie.
Gone are the days of riding the lanes with a £90 Ribble Audax frameset :)
https://www.ribblecycles.co.uk/ribble-cgr-sl-shimano-ultegra-di2/
The 725 looks pretty good actually
https://www.ribblecycles.co.uk/ribble-cgr-725-frameset/
oh, except for the lack of Di2 routing