I installed a new SD card today in my new system. So new flash on a 3B board and I downloaded all my games to it. Most systems I already have a gamelist.xml file but there were a few new systems I loaded due to having more space on the new SD card.
I just used the built-in scraper for 3 different systems - Master System, Gameboy and Atari 5200. It worked fine and was very fast too.
EDIT: I installed the Selph scraper right after posting this and re-scraped Gameboy and Gameboy Color romsets. It worked fine. I had to change the console source to screenscraper and it downloaded videos. Everything seems fine here.