I've mainly never done it because I've had the idea that the worst thing for me is to be "diagnosed", because what I really need to learn is that there is nothing wrong with me (and therapists don't tend to take that angle, from what I gather).
I also think I'd either just whine & want to be heard or have a hard time opening up at all because I find such things very humiliating (I used to really fear crying in front of other people). I have a tendency to be like "I'm fine, I'm fine, I'm fine - SIGH!".
I think therapy only works for someone if they're ready to do work, and the sp 4 is likely to not even do it UNTIL they are ready, whereas sx & so may for the wrong reasons (attention, sympathy...). In other words, I don't think sp 4s are automatically more inclined to self-improvement.... it's just that they're being martyrs in isolation instead of seeking a willing ear in the meantime.
@Southern Kross - you seem very contained. What has led you to settle on so/sp and not sp/so?