The 5S1P 4000mah run lasted a little less than 20 minutes. These are older 10C cells. I've ran them pretty hard all summer in the E maxx, so I doubt they are quite putting out 4000mah anymore. I bought these batteries in Feb.
Battery temps are 120 degrees. Motor is at 100 degrees and the ESC is 115 degrees. All still well within range.
The 5S Lipo setup runs exactly like the 6S1P A123 setup. I couldn't really tell any difference as far as performance goes.
I'll try 6S 4000mah Lipo next. We should see some real gains then.