I'm guessing you're feeling a lack of compliance leading to a lack of confidence going downhill.
This is mostly down to tires and rims--excessively high tire pressure is the single largest factor in poor rear-end compliance.
You can reduce tire pressure while keeping rolling-resistance low by adopting wider tires, wider rims, higher-quality tires, and replacing butyl tubes with TPU, latex, or tubeless tires. The frame is mostly secondary to tire-setup, after all, the pros are riding Roubaix on aero-bikes these days.
What rear tire are you using? What width? What rim width are you using?
For example, I weigh 80kg, I am using 28mm Continental GP5000 with Ridenow TPU tubes inside, mounted to ICAN Aero 35 wheels, which have a 19mm internal rim-width. I run about 80-85PSI for races with high demands on cornering.
If you are really committed to buying another frame, I believe ICAN has the most solid reputation for quality, but their frames are somewhat heavy. And there's no guarantee it will be more compliant than your Winspace.