Hello feiko,lai,
For quick test we've used three chunks with 500 millions points in the dense cloud each, and it took about 6-7 hours (including mesh merging) with the memory consumption peak about 50 GB. We have optimized the merging procedure, so it should be considerably faster now, but the memory consumption would be almost the same.
Then we've used the version with the fix to merge the original three chunks with the merging result, so 3 x 500 millions chunks and 1.5 billion cloud - it took less than one hour, and memory consumption was about 110 GB.