runtime..... a issue for 12th scale Mod (8 min heats )and at our track for Mod TC (5 min heats) both will/can dump before race is over depending on driving, motor, etc.
voltage..... plays it's hand best in any stock class
packs with both on the hi-end have a higher average voltage thru-out the heat
i have seen packs rated at 1.170v 424 sec put out a higher average voltage in a 5 min test than a pack from rated at 1.178v 395sec (both from same company)
things that make you go HMMMMM........
most cars ran in 4-5 minute heats do not draw a continous 30 amp rate or do they drain each sell down to the .9v each cell cutoff.
after about 6 races, the numbers on your pack can get worse or better depending on how you treat them. either way the cells start drifting and the pack, ideally should be rematched for accurate numbers