1. You still have nearly 30 years ( assuming a 65 retirment age) to build up another tax free lump sum on retirement. Its just the right to take a tax free lump sum from the pension relating to this employment you are waiving.
2. If rumours are true, then this tax free lump sum might not even be permitted by the time you come to retirement anyway. We'll see what happens at dec budget.
3. By waiving the right ( and taking €10k now) - you still get the same value of pension - all you are doing is waiving the option to take it in cash form. If you have AVCs you can still take them as an ARF, and in cash form, taxed.
If I were in your shoes I would waive it.