I think the new format makes it substantially harder (assuming you actually want to win the tournament) to play all U23 and second choice players in the group stage. Not only is the pool of group stage teams stronger than before, because a lot of the weaker teams are now in the conference league, but you're highly incentivized to win the group, as that gets you a bye into the R16 whereas finishing second in the group means you not only have to play in the R32 but its against one of the eight teams dropping down from the CL. Last year that included Barcelona, RBL, Porto, BVB, Atalanta, and Sevilla. Essentially, finish 2nd in the group and not only do you have to play two extra games during a busy time in February but its likely to be a difficult tie.