My experience is similar. I have a condo at the beach that in rent as whole house. I've listed on dozens of different site and as the vacation renatal / home sharing evolves. Right now it's HomeAway and VRBO.
Before joining Airbnb earlier this year I was exclusively listing on HomeAway and paying for top placement. This had happily kept me fully booked during the season for the last 3 years. This year my inquiries and booking rates dropped way off as HomeAway changed to be more like Airbnb. (Eliminated the premium hosting options, changed the placement algorithms and pushed online booking and instant booking.
Airbnb has filled in nicely and I notice that my advance bookings (greater than six months) come from HomeAway and the near in bookings less than 3 months in advance come from Airbnb and they split the 3-6 month window.
I think Airbnb would source more of the advanced bookings if they would accept deposit and final payment scheme versus full payment up front. I also like that that HomeAway handles the transactions and I have control over refunds and a more traditional security deposit arangment.
In terms of support I actually give Airbnb better support. The queue ones are shorter and any of my issues were handled quickly and equitably. They don't post thier contact numbers for folks to find easily but searching contact Airbnb on google is not difficult. That is in fact how I found this community forum.
I am a huge proponent of booking on multiple sites and I may try booking.com next year. However if you do this it's imperative to have a system to manage things and ensure no double booking. I don't recommend instant book on any of the sites and would recommend either VRConnection.com or onerooftop.com.