Thanks guys. Been thinking about this overnight some more. Wondering if those fairly high ratings on the notebook adapters are allowing for the case where it's charging the notebook battery as well as running the thing. So if the notebook is already fully charged, it will draw much less?
Still, sounds like I've been pushing the capability of the Belkin and risk it overheating or something. It has a fuse on the back of it, so hopefully that would protect equipment from damage, but still...
Looking at Jaycar inverters rated for 300W,
there's one for $85 and the closest
one with pure sine wave is 380W and it's $270! Worth that much more, considering that DSLR AC adapter and the notebook adapters both may handle non-pure sine wave type input a little better from what I've read? (The USB hubs don't, though)