I agree 100%
MS SW factories could be very helpful on certain cases.
The EntLib is really helpful in terms of supported functionality and versatility (very customizable through config, good configuration tools), but it is very heavy in terms of total assemblies' size required.
Another aspect to be considered is the learning curve that must be traversed by architects, designers and devs to be proficient with the use of these tools.
Each team will have to balance between (custom) code construction and third party code adoption.
This is a typical Build or Adopt type of decision (I prefer to use the word Adopt instead of Buy, to include both Commercial and Open Source Libraries).
