Road bike purchase advice

In the next year or so I'll be turning 50 and I'd like to celebrate with a new bike. I currently have a steel Dawes Audax Supreme that I use for everything (Commuting / recreational use / the occasional event). I love the way it rides - it seems to be quite compliant and absorbs the imperfections on the dreadful road surfaces that we have in the South West. I'd like to continue to use this for commuting and also to experiment with bike packing in future.

What I'd like is something a little faster whilst retaining a comfortable riding position so I can do events such as the Dartmoor Classic. I guess that I am after a Endurance bike wha would people recommend? It needs to be under £3k and ideally on the CycleSolutions Cycle to Work scheme. I'd quite like 105 Di2 and think that a threaded bottom bracket is preferable to a press fit bottom bracket. I should say that other than an old aluminium hybrid I haven't ridden any other bikes. So far I have considered:

Sonder / Dolan (titanium) too heavy?

Cannondale Synapse 2 (don't like the integrated lights as this is just something to go wrong and I'd rather sort out my own lights). I am slightly nervous about the lifetime / robustness of carbon bikes.

A friend of mine has suggested a Cannondale SuperSix Evo3 but this sounds way too racy / not sufficiently comfortable.

Thoughts?

Mark