I mostly agree, but it's worth mentioning that lactose intolerance rates are very dependent on ethnic background -- you're far more likely to tolerate lactose as an adult if you're of North or West European ancestry than just about any other ethnic group, so weight your estimates appropriately. Degree of intolerance also varies -- a full glass of milk will give me problems but I'm okay with cheese (which loses most, but not all, of its lactose in aging), while a friend of mine has trouble with a single slice of pizza.

Personally, I don't usually bother with lactase supplements; the timing is tricky (to be effective, they need to be taken twenty minutes or so before consuming dairy products) and most of the recent sources I've read don't have anything good to say about milk for adults, nutritionally speaking. I do miss ice cream, but the pleasure I'd get from it isn't worth the hassle of making it edible.