Ooh, cool thread. Everyone is interested in the love lives of the silent, mysterious INTJs.
Seriously, I think the success and happiness of a relationship has a whole lot more to do with commitment, respect, affection, and all that good stuff than it does with personality type.
That said, I like the idea of INTJ/INFJ pairings-- all other things being equal, and so long as they are mature enough to handle Te/Fe differences. There is a lot of common ground-- (introversion, Ni, etc,) but enough difference to keep things interesting and promote personal growth.
In my highly humble and uninformed opinion.
"There ain't no doubt in no one's mind that love's the finest thing around. Whisper something soft and kind." --James Taylor
Based on my experiences with INTJ girls.....I'd advised against the whole INFJ/INTJ pair. If it works, I guess things would be fine. If it doesn't(like it did with me), well.......let's just say you have one incredibly shitty mess to clean up.