Lane swaps would have been fine if the solos got a real level advantage.

But since the shared EXP is cut in half and then increased by 30.4% the solo is never going to be level 6 while the duo is level 4.

There is no major trade off of gold income for exp due to this 30.4% increase.

http://leagueoflegends.wikia.com/wiki/V1.0.0.138 This is the patch in which it was increased from 26.1% to 30.1%

FYI games like dota 2 do not have a boost for shared EXP and they sometimes have triple lanes but also do not have a Support + ranged attack damage carry meta locked into place.