True and false.
When talking about possessive or attributive, 之 is not a pronoun. It is an auxiliary word similar to "of" which is categorised as preposition in English.
As an auxiliary word, it could connect both possessive and attributive modifiers with the subject they modify.
According to the The Standard Dictionary of Contemporary Chinese
Copyright © 2010, 2012 Oxford University Press and Foreign Language Teaching and Research Publishing, Co., Ltd
Translation: Used between modifier and subject to construct possessive or attributive modified phrases.
赤子之心 | 大旱之年
Translation: heart of patriot | year of grate drought
Translation: used between the subject and predicate of a subject-predicate phrase and convert it to a modified phrase
影响之深远出乎预料 | 速度之快
Translation: The far reach of the influence is beyond expectation | the quickness of speed
Translation: Combined with the following single syllable element to construct noun or noun phrase
之后 | 之类
Translation: afterwords (maybe it should be the descendants here?) | the alike
I wrote the above translation. They may sound very odd in English because those are meant to demonstrate the construction of the phrase.
So the question is concerning usage 3-a and 3-b. And I'd say it is more common to see 之 use to connect possessive modifiers than attributive. But it doesn't seem to be a very drastic gap. Maybe it's just because there are more alternatives for attributive constructions. E.g. 美人 (beautiful people), it's a quite basic construction and there is no need to interpolate it to 美之人 unless the author has some special needs like matching sentences or something.
And according http://baike.baidu.com/view/42455.htm, in Classic Chinese 之 can be used for both as well. So whether one usage is more "usual" than the other is really a statistical issue. And I don't know any such statistics. But according to the examples on the aforementioned page, possessive usage seemed to be slightly more common.