Get yourself to Ribble Cycles. Carbon Sportiva with latest Ultegra groupset for £999
You just have to be patient and look out for the good sale offers. can get 105 from £800 upwards. Unless you cat race then there is no need to have a mega stiff frame...
Owners who should've bought something that fits their requirements. You buy a Ford Focus, don't expect it to do 200mph.
The Planet Flex comment is derived from owners. The snobbery comment is born from an assumption which is incorrect. Yes, you won't get a stiff frame at this price point but that's precisely why the reference is common and not a matter of snobbery but an observation - one which you yourself just confirmed to be correct. "They're not called yellow jelly beans, that's snobbery! But they are yellow and made of jelly,".
They're not called planet flex at all - that's just bike snobbery. I really do wonder what people expect though, at that price point. When they do their £999 Ultegra/Force deal, you're getting a £600-£700 groupset on it and a £130 wheeset and that's before you think about the saddle, bars, and all the other bits. You are almost getting the frame for nothing. It's bound to be a cheap carbon frame that will have some flex under power. What you're getting though is some of the benefits, like very light weight (mine comes in just over 8kg), a comfortable ride and a frame that copes well with the less than perfect surfaces we have in this country. I'm not Marcel Kittel so I don't notice the flex. But if you do, I'd suggest you spend more on a bike.