I now have a Roubaix Expert 2021 and came from a 15 year old aluminum bike - the difference for me is extreme. I feel like riding on a comfy chair, but still far more agile and with better handling than my old bike. Part of it are the broader tires (28 for the Roubaix at 95psi vs 23/25s with 125 psi on my old bike), but the seatpost and the FutureShock make it a very smooth ride - when climbing in a standing position I lock the FutureShock out, otherwise it feels a little weird, so the 2.0 version is a must in my opinion (the Pro has it).
I'd definitely buy it again, but I have no comparison to other modern bikes.