I much prefer the RTW trade system mainly because of what you mentioned above, but also because your provinces trade with one another.
If I remember well, CBR inquired about the income and found out that H and VH settings give you "income penalties". I think you only receive 94 % of the normal income on H and 89% on VH. In the study he carried out it was about tax income so I don't know whether it also applies to trade.