Sorry if my nomenclature is wrong. What are the pros and cons of add-ons (XI & Better Blogs) vs plug-ins (Wordpress, Blogger, etc)? I'm assuming the worst, that both developers of add-ons have jumped ship ("XI" a long time ago and "Better" since October). I have no programming skills. Would I need to pay someone to integrate these into xenforo, maintain or fix any problems?
WordPress and Blogger are separate software projects/services, so I'm not sure what you're asking exactly. I suppose you're asking about a bridge vs a XenForo-designed project?
Bridges just connect 2 unrelated pieces of software/services, often in limited ways. You will have 2 completely separate management systems and 2 separate interfaces (generally). What's shared is dependent on the bridge.
An add-on builds into XenForo so it will be more integrated. One UI, one admin interface, one set of users, etc.
Both need to be maintained across software updates.
I would echo @Brogan, though I would say "maybe" for a second point release. There's a lot of variables in the equation and there will be a difference between "needs to be updated because it broke" (definitely possible, hopefully towards the less likely side) and "doesn't take advantage of new things in the update" (also very possible, depending on what sort of systems are added).
Thanks gents - how about my second question (I know it's not a blog, but what about a product like ArrowChat that calls xenforo a supported integration? Is that an example of a really strong bridge, or is this a different category?)? I'm just wondering if there is another option we haven't discussed.