I too have been a member of both but now only keep an IVAA membership. I dropped my VAInsiders membership when I felt I just wasn't getting my money's worth. Earlier in my VA business, it seemed to be the perfect fit but as I progressed, I felt like I had outgrown it. That's not to say it wouldn't be exactly what you need because Tawnya does provide excellent resources and seminars.
I went to the IVAA Summit in Phoenix and was able to meet so many of the amazing VAs I had admired online. I must say I was just blown away by how welcoming everyone was and it was definitely an experience I would love to repeat! The IVAA Yahoo Group is great and I haven't once regretted buying my IVAA membership, my only regret is that I hadn't done it earlier in my VA business!
Good luck and let us know how it goes!