Starting from scratch sucks but it can be good as you don't make mistakes made the first time. I did it and I'm finally around the same level unit-wise for my core team.

Of course the difference in units has good and bad (good I have Themis, Adele and Elizabeth, bad I don't have Jerome, Despara and all the units from events before).

It is a lot slower going free to money as I'm not getting the better stamp cards and I can't power level like I used to. But I can lean on units from events to compensate a little. Really depends on what comes up, how strong I can get it and how it fits into the team. Before I had that plus rolling the gacha.