If I invest in a developement I need to see the accounts of the developers and be clear that their finances are managed very conservatively. I would want to see evidence of a strong balance sheet, strong cashflow, and to see that their development costs are easily covered by, and not relying on too many factors to come together to avoid the whole thing falling apart.
Now I cannot categorically state that Harlequins developments are going to fall over, but I cannot look at their accounts and know how robust their business is. So you might trust Harlequin to deliver for you but I would not take a risk like this where their financial position is not 100% clear.