I'm an INTP and Ennegram 5w6.
Lenore Thomson (Personality Type: An Owner's Manual) has an interesting take on MBTI types and defense mechanisms related to the tertiary cognitive function associated with that type. A short excerpt for INTPs:
"Introverted Sensation also focuses the type’s defenses on issues of material well-being. Such INTPs worry about the effects of others on their health, or about the harmful aspects of food or the environment, and they circle the wagons accordingly. Sometimes they strike others as hypochondriacs,
but their physical states often mirror the emotional states they aren’t recognizing in themselves.
INTPs of this sort are attempting to limit their perceptual intake to the familiar, but the result is the increasing influence of Extraverted Feeling. As Extraverted Feeling gets less conscious and more powerful, it begins to actively oppose the INTP’s dominant approach. INTPs in this position are likely to draw attention to themselves. They’re hyperaware of people’s reactions to them, and they respond with vehemence. Extreme INTPs are frequently embroiled in disputes with people, and they spend a great deal of time and energy defending their thoughts in journals or on the op-ed pages of local newspapers."
Another component related to TMS in INTPs is inferior extraverted Feeling where harmony and a connection to other people is desired while not being good at handling one's own and other's emotions. This leads to avoidance of interpersonal conflict since INTPs feel inapt at handling it which can easily result in a "be always nice and good so that no interpersonal drama ensues" attitude.
http://personalityjunkie.com/ has a good introduction into types and the theory of cognitive functions plus very good and detailed profiles about how different type think and the resulting behaviour instead of just focusing on superficial traits like most profiles do.
https://sites.google.com/site/upatel8/personalitytype5 is a very detailed description and analysis of Enneagram 5 (with linkes to other Enneagram types), talking about different levels of healthiness, basic fears, coping mechanisms etc. I can see how the Enneagram 5's fear of being incompetent can lead to perfectionism as coping mechanism.