Is hearing Krsna's janma-lila an obstacle?

First of all we have to clarify what is meant by "an advanced devotee". Reading about and meditating on asta-kaliya-lila are elements of raganuga-sadhana and bhajana, so “advanced” in that case means one who is genuinely qualified for raganuga-bhakti and specifically in madhurya-rasa, which is the focus of asta-kaliya-lila.

A raganuga-bhakta will customize their sadhana and bhajana according to their specific inclinations for a relationship with Krsna with the underlying principle being to do that which is favorable and direcly nourishing for one’s desired goals. Here is an excerpt from VCT’s Raga-vartma-candrika which addresses this principle:

The scriptures show five kinds of devotional practices to make it clear which limbs of bhakti are to be practiced in rāgānugā-bhakti, what they are like, what is their actual nature, what is to be done and what is not to be done.

They are those which are:

(1) filled with one’s desired mood (bhāva)
(2) related to one’s desired mood
(3) favorable to one’s desired mood
(4) not opposed to one’s desired mood
(5) opposed to one’s desired mood

Of them, some are both the practice (sādhana) and the goal (sādhya) (the only difference being that the former are in an unripe state, and the latter are ripe), some are the direct cause of attaining the goal (prema), some are the indirect cause, some are helpful, some are harmful, and some are neutral. All these divisions have been shown. RVC, 1.13

All other limbs of devotional practice are attained through the practice of hearing and chanting. Without hearing and chanting one’s following in the footsteps of the people of Vraja will remain fruitless. This was said by the learned sages after elaborate consideration. One should only practice those limbs that are favorable to one’s own devotional mood and not those that are opposed to it. RVC, 1.11