I'd say, higher reward the is splitted. Two reasons
1. No yellings like : "Zomg you feeder, banned wtfqq" if you keep the amount rewarding but still as low as possible.
2. More motivation to play supporter - a big flaw of dota. Why shall i play a hero that only helps peep (PoV of a public player), if i just can run around with Hero-Killer XY and go godlike so everyone thinks i got the biggest epeen!
Your statement : 60secs with one less is not alot, you maybe get xp bonus and can take a tower down. For example dota. If you manage to kill your opponent hero (on the solo lane) + wrecking his tower + gettin 1-2 lvl above him.. the game mostly is already decided.
So loosing a player on a competitive lvl is the bigger issue than the gold the others got. I mean.. lol even 300gold would equal 2 killed priests, so farming creeps is more effective than heros. Even in Dota. A kills gives 250gold, but a creep 40. In 30min, you can make 200 last hits.. or around 10 hero kills (still talkin about competitive or say, effective way of playin). 200x40 = 8k gold , 10x250 = 2.5k.
Ever watchet SK-Gaming etc. Dota-matches? even for non-dota players they can be quite intressting and show a total other way of playing dota.
Rewards yes, at best for the team, but nothing to great.
So long, Aspartem 