I have several times thought of using the lore established currencies as an argument when discussing mechanics that don't need to get implemented into the game for it to follow the d&d setiing. As stated above, it doesnt really bring anything to the game experience unless you like stock market simulators. So for me,, just having gold or coins as one currency is enough. Backpacks on the other hand is something I would like and unless they have changed the encumbrance to not allow your party carry twice the amount of weight that is stated that they should be able to, I don't agree with Tuv. If my character inventory states I can carry 80 pounds...I should feel the effect directly passing that threshold.
