I do not own a license for Snog's addon, however, I do own an IPS license and can tell you that Clubs is fantastic. You are right, it is very tightly integrated, as is all their products, and honestly nothing compares in my opinion.
I would recommend reading about Clubs and Snog's addon and compare them.
https://invisioncommunity.com/news/product-updates/new-clubs-r1017/
https://invisioncommunity.com/features/content#clubs
https://xenforo.com/community/resources/social-groups-for-xenforo-2-x.5651/
If you are very keen on using XenForo, you could wait for Nobita to release his social groups add-on. I haven't used it, but just from looking at it and reading other people's reviews, it seems like the better choice. Although, I have read that Nobita's add-on has stability issues, which would be less so in IPS's clubs. I don't know if that will change in his w.x version.