Thanks Ann, I'm so glad you took the time to address these issues.
Re point #2, I agree that the Boston market is approaching the top of a bubble. The question is not IF it will burst, but when and how much. But let's say an owner-occupant buys a triple today for $600K for a long-term hold, let's call it five years. Each month he's out-of-pocket $1K (due to living in one of the units). He gets favorable financing for first time home buyer (3.5%, 30 years, and just to make it simple let's say it's 100% financing). And let's say the alternative to buying is renting for $2K/month. So he's ahead by 1K/month. At the end of five years the loan balance is $537K, and he's saved 60K versus renting, so he's in for $477K, 20% less than he paid. So if the market is down 20% he's at breakeven. What is the likelihood of that being the case, who knows? If he simply rented, we can be sure that he'll be out of pocket $120K after five years with nothing to show for it.
Re point #4, the idea is to try to mitigate risk by buying at a price below the regular MLS market (although it has other risks).