here’s my two cents,
granted condo conversions are old, not well built. but would it pencil out as a rental when you and your family outgrow it and get sick of it. (and you will). if you would be cash flow positive with the condo as a rental, buy it. but make sure you kept money aside so when you want to purchase a real home in 3 years you have the down payment to do so.
another thing to consider is how far along the project are these guys? are they almost done and out of there? if so, you are a lot safer. if these guys are not half way thru with their sales, you may be looking at purchasing a unit in a property that might go back as a re-apartment. I do believe there are stories already circulating about some SD condo conversions doing that already.