@cronleys, I agree with your logic, and ignoring the pension risk for a minute, the return on investing in your pension assuming you are at the higher tax rate is way beyond even what the variable mortgage rates give. You would be paying your mortgage down in after tax Euros vs the pension which is (mostly) before tax.
Regarding ETFs vs mortgage, yes ETFs has a risk associated with it, but then so does paying down debt. Lots of "rich" people use debt as an inflation hedge. IMO once you get the monthly payment down to a manageable level, and what manageable means is very subjective, investing ahead of mortgage payments becomes a good option.