Tinker, the main risk of tracker funds is that associated with equities in general ie you could lose the capital you invested. Other lesser risks include equities being relatively volatile over the short term and not performing as well as anticipated at the time you cash out your pension into an annuity at retirement.
Tracker funds are funds which track a specified index, like the FTSE All-Share (UK) or Dow Jones (US) or basically any index out there, depending on which market you want your exposure to be in. As contrasted with actively managed funds, the management fees for a tracker fund are relatively low and you get the exposure in the market you select without management fees eating into the returns. The disadvantage is that because the index passively tracks the index, if that sector is doing badly in general, you do not have the hope of a competent fund manager picking stocks which would give you a better return than the index. But by the same vein, if you end up with a dog fund and a dog fund manager, your actively managed fund could likewise underperform the index at any time, with its high management fees to boot.
I prefer trackers over the long term (esp for pensions and Child Trust Funds) because all you want is really to follow the stock market as it climbs up over the decades, and any volatility in the meantime, can be smoothed out with dollar cost averaging (ie drip feeding amounts into the pension every month) and are largely irrelevant anyway until you decide to cash out on retirement.
By all means, seek the advice of a reliable IFA who can check the risk profile of dh/yourself to ensure that you don't get into any fund that is over your head. If your pension allows, you can choose a selection of funds, rather than just one fund and change it over time as well.
BTW, my company pension allows me to select a menu of funds, one of which invests in commercial property, so I have some exposure through my pension in UK commercial property as well.