I managed to get that OSM2XP program going with pretty decent results for Lisbon, hope you don't mind me posting a couple in this thread:
Heading out of downtown Lisbon in the BK117:
Flying over Estoril Race Track:
It looks like the results depend on the source data in OpenStreets, but so far I'm pretty pleased with the results especially for freeware, and I'm sure if I can locate some detailed mesh for the area it will help too.
I echo your findings on directory size, with all the freeware scenery I've downloaded for XP10 even in the last few weeks, I can tell it will easily take up more disk space than FSX.
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