Don't take this the wrong way - Im enjoying the discussion, but here's what I think the weaknesses in your argument are:
1. Sample sizes - far too small in each case. And of course, once you deviate from a 2/4 snare pattern does that automatically mean its 'Latin'? You would need some very firm definitions to back up an analysis like this.
2. Too much emphasis on the Latin influence on dancehall. Sure, there is a strong thread of Latin influence in Jamaican music, particularly from salsa in the 40's/early 50's, and some early rocksteady and reggae tunes are at least partially based on Latin standards, but even in that sense, New Orleans, Rasta, Burru drumming, Mento... are much stronger influences. Also, Carribean music in general shares some of the same rhythmic characteristics, Calypso, Son, Merengue, Soca, Salsa, Mento... so it might be more accurate to see African traditions as a common influence rather than Latin music influencing everything else.
With regard to dancehall itself, it was around for 10 years before Punanny introduced the boom-boom-chick pattern, and it's one of the most rhythmically promiscuous genres around... Hip-hop, Pocomania, Kumina, Banghra, Mento & various Reggae rhythms are all utilised, there was a huge amount of output, tons of studio experimentation, loads of competition between studios and producers... so Im not sure exactly how much you can pin on the Latin influence.
Many Jungle producers were fans of dancehall, or at least exposed to it, and as such absorbed these Latin-indebted rhythmic idioms.
In 1994, complex, mutated Latin rhythms (by way of dancehall) came to dominate Jungle. Presumably this was a subconscious process, but I don’t think it’s impossible that some producers tried to make dancehall rhythms using breaks and in the process came out with something bossa nova-ish.
This is the main problem here I think. The thesis is inherently unprovable. Im pretty sure most of the producers of those tunes would say that they were simply trying to make breaks work in the studio.
Also, the chain of influence all seems a bit doubtful... dancehall, strongly influenced by latin music - maybe. Jungle producers absorbing these 2nd hand influences subconsciously and producing something 'bossa-nova-ish'... ...doesnt seem hugely convincing to me.
The fact that ragga jungle (i.e jungle explicitly referencing dancehall) was more likely to use bosa nova- ish rhythms than non ragga jungle, leads me to believe that there is a direct (yet subconscious) lineage to dancehall, rather than arising merely from from production experiments.
On the other hand this might just as well weaken your argument... Tons of dancehall samples included bass, drums or other rhythmic elements as well as the vocal, so it would make sense for jungle producers to build around these elements rather than fight against them. If the influence is less present in non-ragga jungle then this could show that there was no pervasive influence, just a reaction to the musical elements present in some of the source material...
Still, entertaining theory. Id like to see a systematic analysis of common jungle break combinations and variations with comparisons to various Latin patterns, cross referenced with an overview of the commonalities of late 80's and early 90's dancehall riddims and their sales figures/penetration in the UK reggae scene X the probability of their exposure to future jungle producers....
