I just returned via VIA, and all they required was that I buy a bike box for 20 bucks, and they also gave me an enormous box for extra junk like the helmet I carry, my new super rack that won't fit in the Bike box, tent, sleeping bag. Without the awkward rack I could have put all my bags in that box. I didn't have to sign a waiver, either time I have done it, but I wouldn't really count on getting paid if they pouched my bike. Which they haven't either time. I mean the real problem is ending up at the begining of your tour with a wrecked bike. Good luck getting the bike fixed, and an offset for your lost trip costs.
The only major hassle is carrying a pedal wrench of serious enough dimension. It actually proved useful for a few improbable chores, from tightening pedals to removing the blades from my parents lawn tractor which improbably for an american icon like John Deere, are 15mm bolts.
If I go to europe, it will probably be on a bike friday. I have been accumulating construction info for a while for that.