The liverepeater (origin/edge) is completely separate from the Load Balancer. The LB distributes connections only, has nothing to do with streaming. The LB only tells a client which edge server to connect to. I try to explain in more detail here:
http://wowza.com/forums/showthread.php?9419-Load-Balancing-Issue/page2#13
The EC2 small, large and x-large instance types get about 150, 250 and 350mbs resp. The small is most cost effective cost/bandwidth.
Another option is use subscription license to run a cg1.4xlarge:
Cluster GPU Quadruple Extra Large Instance
22 GB of memory
33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core “Nehalem” architecture)
2 x NVIDIA Tesla “Fermi” M2050 GPUs
1690 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
API name: cg1.4xlarge
You can’t use this instance type with Wowza devpay, you have to use a subscription license.
This cost is $1.60 an hour (Us East region, other regions vary) + subscription cost ($65 a month) + bandwidth usage. But no origin/edge configuration needed.
This is a very new instance type. It is perfect for this use case, but it is untested.
Richard