To expand on this, DB administrators tend to be a conservative bunch. To some extend you can make a slow DB fast by spending big on hardware. No amount of money however will make an unsound DB reliable.
I think it is obvious that no one will want to put their valuable data in an 'unsound' DB.
To restate my original question: If you had two database systems that were equally reliable, but of course had different strengths and weaknesses, would the ability to update large tables without significantly impacting general query speeds, be a major factor in deciding between the two?