ST,
In airlines with rates of pay determined by "weight/speed formula" (most US carriers) the larger the aircraft, the higher the pay rate. The other part of the formula is pilot seniority. The more senior the pilot the greater his/her opportunity to hold a position on a higher paying piece of equipment. To further confuse the issue the pay rates are increased year over year in accordance with the pilot's longevity.
You mention rates of pay determined by longevity and the airlines that employ that process. One is not better than the other they are just a little different.
I do not see any inherent safety issue in movement from right to left seat on a particular airplane, rather it is one of personal preference. I do agree that it is better to start your command career in a short/medium haul a/c rather than long haul.