With one exception, all 3rd party video FX plug-ins loaded into VP17 without a problem (so far anyway): BCC, Mocha Pro, Magic Bullet Looks, NewBlueFX.
The exception: HitFilm Ignite. Even re-installing Ignite and rebooting didn't help. It looks like Ignite is not really fully OFX and is locked to NLE versions/builds. HitFilm say that you can keep using Ignite if not resubscribing (which I haven't), but they don't say that Ignite is not fully OFX and therefore won't work in later NLE releases. They'll likely release a new Ignite update supporting VP17, but then I'll need to resubscribe to get it, and the subscription cost is about 80% of an outright purchase - very, very expensive compared to other subscription/upgrade rates from other NLE and 3rd party plug-in companies.