Oh, and I did isekai my party, when they got too powerful to run in Middle Earth. Divine interventions gets rid of any minor problems!
That's awesome! I wish my party members had enough attention span to stay with one character and level them up but they'd get bored and accept the reduction in levels to play something new. Level 3-5 characters won't cut it in the
Barrow Downs (I played it when it was a new scenario...) and the GM tosses enemies at the party that my 10th Level Rogue has trouble with.
I agree with the currency part -If MERP gold coins aren't devalued, their weight value will be fine, unless gold is so common in SW that
everything
is made of gold... Most monetary standards in RPGs are generic: Elf, Human and Orc gold have the same weights and values, so the monetary system isn't so complicated (the Medieval method would be used, just using scales to determine value and as a RL jeweler, I know methods of determining the purity of metals).
Dropping players into Medieval Europe would not be much of a problem, a little time for getting used to primitive variants of languages but nothing impossible. Getting dropped into a totally alien world will take time and players would have to devote gaming time to gain language fluency. Again, not a critical problem, so I'm not worried at all.
I think of the Roman Empire at near its collapse, under Augustus (27 BCE) a denarius was 90% silver and the remaining 10% bronze (that alloy made coins last longer in circulation), by the reign of Gallienus almost 300 years later, a denarius was only 5% silver. Sure, the government could mint
more coins but people knew the coins were using far less silver so prices (which increased 1,000%) reflected that fact. By that time, only Barbarian mercenaries were paid in gold.
...End economics lesson... Right now I've opened negotiations with the GM on how we're handling the transition from ME to SW. I've been playing my current character on and off for five years and other players have come and gone. I have items crafted by Dwarves in Moria, which the GM said would be similar to owning divine artifacts in SW and he's cool with that, I earned them, especially the ogre skull mounted in mithril that I use for a drinking vessel...