New vs preowned

Hi I am getting my first roadbike, and I am finding the whole process very difficult. I am torn between getting a brand new bike, or getting a preowned one.

I absolutely love the look of canyon aeroad, and I feel quite sure that is the bike I want to get.

Currently on marketplace there is a 2023 canyon aeroad CFR that comes with power meter and pedals. It doesn't have the gear groove attachment options, which is a downside, since i might want to get the aerobars for triathlon. It has upgraded wheels, zipp 454 NSW, and looks in good condition. Owner says he has ridden about 8000km on it. Price is 5300,- euros. Maybe I can get him a bit lower.

On the other hand, I could get a brand new SLX 7 with shimano or SRAM, add pedals and power meter for around 5000,- euros.

What should I do? Any advice on this would be appreciated 🙏