Unless you have a specific hardware or software limitation, You save 20-60% of hard drive space without losing any quality. However, when the need arises to burn a physical copy or use legacy software, converting CHD to ISO is straightforward.
if [[ $# -eq 0 ]]; then echo "Usage: $0 <chd_file(s)>" echo "Examples:" echo " $0 game.chd" echo " $0 .chd" echo " $0 /path/to/chds/ .chd" exit 1 fi convert chd to iso