I am not Microsoft employee. The opinion is completely personal. Many thoughts are from last 5-7 years of using both open source in mix with large vendors as developer.
Monoculture is good:
My personal rule for ASP.NET is to give preference to Microsoft and do not choose 3rd party code (open source or not) unless there is no other choice. Monoculture is rewarding, because you are being carried by big vendor, and quantity of users repeating the same experience is any time large enough to get help and find workaround.
The problem with open source in 2012 is that it is not 2000 or 2005 anymore. Quantity of projects keeps growing, when quantity of users, adoptions, contributors is about the same as years ago. The audiences are stretched thin. Many interesting projects became stale, abandoned. There is no such thing as open source project budget. So when interest ends, there is nobody to honestly announce that support is over and shut the lights off. The projects never die to leave the public attention focus to something better and new. So open source will always keep growing and fragmenting. Having no feedback in form of monetary reward or financial death they are undying entities, existing for the sake of eternal glory.
20 degrees of separation:
Every your adoption of new library separates you from mainstream, shifts you to minority of edge cases. After having 20 steps like choosing security configuration, using particular version, framework, plugin, etc. Your solution becomes a single globally unique combination of details. Googling will help only to proove how rare or unique the problem is. It is always some self serving problem, purely technical. Never even relevant to real business.
Quality comes from focus, money is irrelevant:
There is no stand off of commercial software vs open source. Whole community of devellopers is just one community as it always was. Large vendors simply have an advantage of aging the code longer, in better conditions, with broader audiences than open source groups.
Consensus: You asking if there is consensus. Possibly not. Unfortunately large amount of open source users are way too politicized. After all the open source is a social movement. Open source is immune to critique, because very often negative opinion will be perceived as anti-technological, personal attack. My personal consensus: stick to Microsoft.