Paying tor premium economy seats (O,A,R fares) will boost you in upgrade chances, which will still be tough. If your friends have no or low status, their upgrades chances are abysmal unless they are in premium economy. Even there, their chances are marginal, but at least they are in a better seat if they don’t get the upgrade.

I think you need realize upgrade chances for a group in economy seats is very poor on that route.