Illiyana Amergin:
There are some minor statistical variations on how the D7s and D8s function when compared to the +1 or +2 counter parts, some of which are made slightly less similar due to RPOL's already quirky Dice Roller code but taken as an average they should have almost exactly the net effect same in the long run.
Correct.
But there are some advantages for the use of D7s and D8s over +1 and +2
For one thing, 2's always fail, and considered a roleplaying fumble of some sort leading to ununsual events.
For things like a AC/5 gunnery jam, it's much less likely to roll on d7s and d8s.
Most notably, i use d7s an D8s as a means to use Extreme range, with out making them over powered.
So statistically they're similiar, but they allow the use of campaign statistics.
They were looked at for piloting, but deemed unecessary, since there is no extreme range for piloting... or some such.