Zeca
Manfred Kropp in this paper
https://www.academia.edu/2492924/Tripartite_but_anti-Trinitarian_formulas_in_the_Qur%CA%BE%C4%81nic_corpus_possibly_pre-Qur%CA%BE%C4%81nicthere is a free pdf if you search enough in google, and the author has no problem whatever to speak about pre islamic hajj, he even Quote Muqatil Ibn Sulayman. I guess Manfred Kropp is from the revisionist camp.
Zaotar
correct me if I am wrong, but it seems that your general framework is not that different from Lüling,
"One third of the Qur’an is comprised of the layer of the original Christian hymns, which were transformed
in the Qur’an through the superimposition of Islamic interpretations. The other two thirds include the layer of purely Islamic texts that can be traced back to Muhammad and the textual layer reinterpreted by the redactors who, in post-
Muhammad times, fashioned the final appearance of the present-day Qur’an
The motives for the successive revisions of the Qur’anic text, from its pre-Islamic origins to its post-Muhammad reinterpretations were, according to Lüling, a mixture of dogmatic, historical and tribal motives"
Kropp is an awesome scholar, but he seems to think of Mecca as fully-Christianized, with different factions battling each other. This is where scholarship has generally gone -- either Mecca is turned almost full-Christian (Sinai is another good example of this, with his argument that Q 97 is a Meccan 'counter-Christmas'), or the Qur'an originated outside of Mecca.
At that point, the "Meccan" explanation becomes useless, because it is so indeterminate. Mecca can either be fully Christian or fully pagan; there's nothing you can't find or place there. It becomes what is called, in the field of phylogeny and taxonomy, a 'wastebasket' taxon -- a grouping that is used just to hold unclassifiable organisms, but which does not explain their evolutionary relationships. So this is my problem, Mecca either explains nothing (because it is an indeterminate blank slate that can contain anything) or it actively screws up the interpretation (if you try to make it determinate, as in 'people couldn't REALLY be Christians who were praying to Jesus in pre-Islamic Mecca ... because they were pagans, and hated Muhammad's monotheism').
Kropp's analysis of Q 112 is terrific, but it doesn't hinge upon the Qur'an's early context being Mecca at all. Actually it doesn't even make much sense in Mecca, because why are people speaking in Aramaic in Mecca, rather than Arabic? Again, however, it will turn out that this is because Aramaic had fully penetrated Mecca ... well, if Mecca is chock full of Aramaic speaking Christians, which later Muslims somehow didn't manage to remember, at this point what exactly does Mecca explain as a putative background? It is just a cipher that you can say anything you want about. Once you throw out genuinely pagan Mecca, then you are left with 'forgotten pre-Islamic Mecca' that was full of Christians. This is not an explanation.
Luling has the exact same problem. To justify his Christian interpretations of basal Qur'anic text, he claims Mecca was full of an archaic Christian cult, pre-trinitarian. There's literally no point, from an explanatory perspective, in trying to claim Mecca was x or y in that kind of ad hoc manner. It's enough to establish that the Qur'an contains archaic Christian texts (which I agree with him on). The most likely context for such texts would be in the Nabatean region. But this geographical context does not need to be established one way or another to interpret the text. The interpretation just should not be affirmatively rejected as impossible 'because Mecca was x.' There's no reason to come up with some elaborate explanation for what Christians were doing chanting Christian slogans while making a pre-Islamic pilgrimage to Mecca. All it does is create confusion and speculation, without actually explaining anything.
Generally speaking I agree with Luling's view about the layers of the Qur'anic text, and also his position on what the main layers consist of -- a base of archaic Christian texts which were adapted and re-articulated via secondary Islamic text, and then accompanied by layers of truly Islamic (primary) text. It's his whacky historical claims that I have trouble with.
Topic: what we really know about early Islamic History ?