Yes...going with the Rose in a 53 would be a huge problem. The 50 would be much better suited for you, and I don't think it's too small for you.
The problem is you are comparing an endurance bike (your Bianchi) to a race bike (Rose), so you'll be unable to get similar geometry...you match the reach, and the stack will be too low. Match the stack, and the reach will be too long.
So, if you feel that the Rose in a 50 is too small, then you need to look into other brands that have slightly less aggressive geometry (Cervelo R3 is a good example), or stick to endurance bikes.