Actually now that I think about it, the purchase facility seems to be a bit of a con.
You're essentially giving the State your money to buy a product that will only ever grow at the rate of inflation, and which is a bad trade to start off with (roughly 24:1 annuity ratio).
Funnily enough, if you invested your €10000 in equities as pension for 35 years, took that €100,000 and then transferred it to the purchase facility, you'd end up being able to buy more pension through the facility adjusting for inflation than had you invested in the facility thirty five years ago! (assuming purchase facility cost rises proportional to inflation)