More Apache benchmarks using EC2 instances

Back with more benchmarks ... This time I've tested several EC2 instances, using the AMIs provided by scalr for application roles(app and app64). Site used for testing was mEgo.
c1.medium results:

Concurrency Level: 200
Time taken for tests: 311.715596 seconds
Complete requests: 10000
Failed requests: 0
Write errors: 0
Total transferred: 306810000 bytes
HTML transferred: 303610000 bytes
Requests per second: 32.08 [#/sec] (mean)
Time per request: 6234.312 [ms] (mean)
Time per request: 31.172 [ms] (mean, across all concurrent requests)
Transfer rate: 961.19 [Kbytes/sec] received

m1.large results:

Concurrency Level: 200
Time taken for tests: 420.241673 seconds
Complete requests: 10000
Failed requests: 0
Write errors: 0
Total transferred: 308313369 bytes
HTML transferred: 305097689 bytes
Requests per second: 23.80 [#/sec] (mean)
Time per request: 8404.834 [ms] (mean)
Time per request: 42.024 [ms] (mean, across all concurrent requests)
Transfer rate: 716.46 [Kbytes/sec] received

c1.xlarge results:

Concurrency Level: 200
Time taken for tests: 70.404865 seconds
Complete requests: 10000
Failed requests: 0
Write errors: 0
Total transferred: 306810000 bytes
HTML transferred: 303610000 bytes
Requests per second: 142.04 [#/sec] (mean)
Time per request: 1408.097 [ms] (mean)
Time per request: 7.040 [ms] (mean, across all concurrent requests)
Transfer rate: 4255.66 [Kbytes/sec] received

m1.xlarge results:

Concurrency Level: 200
Time taken for tests: 215.153753 seconds
Complete requests: 10000
Failed requests: 0
Write errors: 0
Total transferred: 308098602 bytes
HTML transferred: 304885162 bytes
Requests per second: 46.48 [#/sec] (mean)
Time per request: 4303.075 [ms] (mean)
Time per request: 21.515 [ms] (mean, across all concurrent requests)
Transfer rate: 1398.43 [Kbytes/sec] received

So to sum things up:
c1.medium can serve about 32 requests per second for 0.20$ per hour.
m1.large can serve less than c1.medium, around 24 requests per second for 0.40$ per hour ... not nice :(
m1.xlarge can serve 47 requests per second, but it will cost you 0.80$ per hour.
The champion is c1.xlarge can serve 142 requests per second at same price as m1.xlarge, 0.80$ pe hour.

I didn't include m1.small benchmarks, but from a previous post I can tell you it only server 6 requests per second, not a worthy instance.

My advice would be to go with c1.medium instances since they offer best price/performance ratio. But do the math for yourself!