The feel will have undoubtedly changed bit due to the different tubing and slightly different tube layout – most noticable is the loss of the curved top tube and introduction of swap outs.
The new frame certainly doesn’t look as pretty but more utilitarian but there are definite benefits – chainguide mounts, swapouts, tapered head tube and buying new will give you a lifetime warranty – I doubt (and hope) On One are not going bust any time soon.
I would be tempted by a Ragley Ti but the price is just so much higher and I do like the ability to run a short fork on the 456.