I would go with the speaker that has the better highs which I would suspect would be the Ref. 1s. With the 207/2s you are paying for what I believe is outdated technology and a good portion of the speaker that won't be used when paired with the subs. If your subs are located close to your mains you might want to try an even higher crossover point just for fun.
Someone please talk me out of this
I use KEF Reference 1s supplemented by a pair of Velodyne HGS-15s controlled by a SMS-1 bass manager that provides acoustic room correction. I think the sound is superb even with large orchestrations since I raised the crossover of the subs from 40 to 80 Hz. BUT I think I’ve found a pair of KEF Reference 207/2s for $7200, and I’m very tempted. The preamp is an Ayre KX-5/20, amp VX-5/20, sources Roon via QX-5/20 and discs via DX-5 DSD. I previously used KEF 107/2s that I loved. but I suspect the combination of Ref. 1s and HGS-15s is superior.