Re: Downsides
I think we're getting our wires crossed here.
A 35-year-old can contribute 20% of his/her salary to a pension each year, subject to a €254k cap on earnings (i.e. the maximum employee contribution is €50,800 in any one year). The 20% is the employee's limit and has no bearing on employer contributions.
Apart from a basic requirement that they make a "meaningful" contribution, employers are free to pay in as much or as little as they like on top of this. The only restriction is that the ultimate pension cannot exceed two-thirds of final salary.