You two (and the folks who agree with this assertion that "it takes just as long to recoup cost for a small ship IN a small ship as it does to recoup cost for large ship IN a large ship") are wrong. You're wrong because of the fundamental confusion many players seem to have with factoring in the _time_ element of trading. It's the same fundamental problem as people who think "my 2300 cr/ton trade route is better than your 1800 cr/ton trade route".
Let's do the math with fully A-classed ships, assuming you're a good trader capable of finding trade routes that are worth 16,000 cr/ton/hour (which won't vary significantly regardless of ship size/speed/cargo capacity--it's a PER TON unit of measure):
Viper: 22 cargo space x 16,000 cr/ton/hour = 352,000 cr/hour = 23 minutes to earn the insurance rebuy
Cobra: 60 cargo space x 16,000 cr/ton/hour = 960,000 cr/hour = 22 minutes to rebuy the Cobra (and only 9 minutes to rebuy the Viper)
Python: 272 cargo space x 16,000 cr/ton/hour = 4,352,000 cr/hour = 102 minutes to rebuy the Python
That's not good scaling for an ongoing maintenance cost.
Next consider that it's dirt easy and fast to get into a Cobra, and only a handful of hours from there to move into a T6. Most people can _easily_ earn at T6/Asp rates with very little time invested. The T6/Asp can fund their Viper/Cobra rebuys at the following rate
T6: 100 cargo space x 16,000 cr/ton/hour = 1,600,000 cr/hour = 5 minutes to rebuy a Viper, and 13 minutes to rebuy a Cobra.
So _most_ players are going to be able to fully rebuy their Viper/Cobra in 5 to 13 minutes, while Python owners require 102 minutes per rebuy. DOES. NOT. SCALE.
Rep for clear and evidence based argument.
I'm only at Asp level, where costs are still reasonable. I think I'd be happy with a slightly longer time to rebuy for bigger ships, but it sounds too much at the moment