Hi: generally homes in the woods portions of Lake Forest will sell for higher prices per square foot than non-woods and non-lakes homes. However there can be some downsides to woods homes: they can often be dark due to the loads of trees, for the same reason it can be difficult to grow regular lawns in some of the woods locations, because of the fence ordinances you often can not have a block fence nor even a regular fully closed wood fence which affects privacy etc.
However, people that love the woods, really love the woods. It is such a unique location and can really make you feel like you are up in the mountains somewhere (go get that feeling anyplace else in OC). Usually the homes that may be on stilts are built that way because they back to one of the ravines. Those homes, because of their views, are often the most desirable and priciest of the woods homes.
As has already been said here, having a competent physical inspection is always of utmost importance on any home purchase. If a good inspector (or your Realtor for that matter during their visual inspection) sees any red flags such as cracks in the walls or doors that won't stay open etc. they will possibly recommend a further inspection by a geological or structural inspector. In fact, if a buyer in escrow is concerned even without seeing any obvious stuctural or geological problems, they can always pay for a structural/geological inspection just to set their mind at ease.