I presume you mean is the PRO 1 worth the extra £300.
Isn’t the only difference that the 1 has Ultegra Di2 as compared to mechanical Ultegra on the 2. I’ve not used Di2, but I imagine it certainly has advantages, and it would cost more than £300 to upgrade later. If it were me, and I had the extra £300, then I’d probably go for the 1. However, if the extra £300 was a stretch, then I’d be more than happy with the 2.
FWIW I absolutely love my 2015 Defy Advanced Pro 2 with mechanical 105 and cable discs.