IF you have serious litigation risk from your job, then a trust may make sense. I personally would never use a trust only for asset protection purposes. However, in certain circumstances, I can see uses for them (mainly succession and income streaming, especially if you have low-income family members).
Costs are relative. Trusts probably cost, what, a few thousand to set up and another 2 or 3k a year to maintain? If you have a million dollars in shares, say, then that's worth putting into a trust. More importantly, since moving from personal names into a trust will involve CGT, I think it makes more sense to do it at an intermediate level. Most people won't have enough assets to justify using trusts. Say you build your shares to a couple hundred k, and there's every indication you might have millions in the future. I would start using trusts around the couple hundred k mark, especially if you have people to distribute dividends to.
Properties are a different matter, since it's probably negatively geared, and I don't plan on using HDTs.
Alex