Endowment; time to jump?

Zoom7005

as we all know that they will almost all show a shortfall in the near future;

but my latest projection is that the 12k units I hold are worth £23k ATM; on a unit price of £1.81 (up 10p since the end of 2007) the policy is due to mature in just under 3 years. Do I continue to watch the unit price and surrender it as soon as starts to plumett or sit tight for a payout of (projected) £28-31k at maturity? AIUI the entire payout is based on the unit value which does not look too bad ATM; anyone have experience of how these things go up and down in troubled times? could they crash and burn completely?

It's Unitised with profit (they suggested I change it to this from a straight with profit in the last recession or else stump up a hefty additional premium) not sue if that makes any difference.

If I pay it for the remaining 3 years their lower projection at 4% is £28k (based on an extra ~ 2k premiums over that time compared to cashing it in. Will I be able to just watch the unit price day to day; it looks like it lost quite a bit last year having gained a lot more the previous 2.

It's (along with 2 other policies; very complex) to pay off a third of the mortgage but given the SVR is so low it's not a big hardship to keep the interest only going until maturity, I have to re-mortgage the shortfall to my additional repayment product at that time anyway.

thanks for any experiences / advice