There aren’t two definitive sets of geometry right? Just like on a mountain bike – all the manufacturers dont use all the same angles with the same lengths. There are different styles within. I’d like a happy medium.
Again that’d be the Defy/Synapse/Roubaix, halfway between the race bikes and the audax bikes.
Pretty much all race bikes will handle much the same.
Pretty much all sportive bikes will be slightly longer CS/slacker HA /taller HT.
I think you’re obsessing over details which will make a very minor differences to the actual ride. A steel bike (probably) wont be stiffer than the PX up front, but will have that intangible astetic that the PX doesn’t and maybe you’ll like it and ride it more and forgive it’s handling as character rather than a cheap carbon comprimise. Or you could just buy a Defy/Synapse or TCR/Supersix depending on what FITS, they’ll all be stiff and comfortable in all the right places, then just ride it! It will probably be better in every way appart from not being steel. On the other hand if the bike being steel and comfortable are the defining factors then what you want is an audax bike, bikes which a lot of people do a lot more miles with a lot more speed than you, it’s not about the bike.