Keep in mind that mercy rules and switching to 1-ball games impact the TGP of the event, which was raised as one of the reasons for wanting to move things along.
Basically, if there’s a set score for where the mercy rule kicks in, all games played on that machine count for 1/3, regardless if mercied or not. If it’s at the TD’s discretion (à la Pinburgh), it’s just that game. 1- and 2-ball games would count for 1/3 and 2/3 respectively.
See Pinburgh "Exceptionally Good Play" - TGP Question for the previous discussion on the impact. (Link goes directly to the clarification of the mercy rule reduction.)
As for custom ROMs, they definitely have their place. I don’t have a problem with them being used in competition as long as the players are advised of what the changes are. I’ve got the unofficial version of the LAH ROM in my game at home and would actually probably be thrown if I encountered factory code in a tournament!
I appreciate that there are folks who are willing to make changes and share them with the community.