I don’t know of a singular reference that compiles downtown condo defects/homeowner complaints. My sources of information regarding these issues are those that live in various condos as well as information from lawsuits filed by condo homeowners against the developer. I have heard of pretty terrible ongoing problems with elevators at Harbor Club, plumbing at Cityfront Terrace and hot water (as in none) issues at Treo. As many of the downtown condos have recently been built, the full extent of problems is yet to be known. I also understand that noise is quite a factor for many downtown condo residents – the train and Gaslamp revelry overflow have been cited to me as sources of complaints.
Not trying to scare you off – I will likely be purchasing a downtown condo myself in years to come – just passing along what I have heard.