If your drivetrain doesn't require the extra chain wrap capacity, there are a few very minor advantages to a short cage derailleur: a few grams lighter weight, and maybe a little more stiffness or durability. But long cages are sort of like the compact crank, which some years ago was considered a stupid offering for old ladies and weak beginning riders. Today many serious racers use them, and we have "sub-compact" or gravel cranks that are even smaller. Most folks are using wider range cassettes now, and smaller chain rings... and most observers don't care.
The velominati will never approve of things like long cage derailleurs, full finger gloves, or widely flared handlebars (let alone flat--gasp!--bars). Heck, it wasn't long ago they considered clincher tires unacceptable for anything but maybe a winter training bike. To be taken seriously by them, you needed tubulars no wider than 23mm, largest cog no more than 25 teeth (27 for hilly courses), and 39/52 or 39/53 chainrings. But they are silly and unrealistic people, and even their standards are changing.
For racing, you should use mostly the same stuff you'd use for regular training and recreational rides: whatever works for you, within the limits of the written rules, of course.