I’ve had 10 speed 105 and Dura Ace, I’ve also got or had 11 speed Dura Ace, Ultegra and 105.
Out of all of them, I’d have 11 speed 105 every day of the week. You wouldn’t think it’d make much difference but having that extra cog fills the ‘gap’ that was previously there – it’s only a noticeable gap if you’ve spent time on the 11 speed before hand but its very noticeable then. I’ve not got a bad thing to say about 105 and I’ll never bother buying more expensive group sets again.
Also, front shifting is massively improved on 11 speed and the brakes are another step forward. If you’re happy to spend the money (the CAAD is worth it), then you’ll not be disappointed