@patch is right, @Ann_Sherwin. The thing to remember is that many accounting programs require a new file for a new accounting period anyway. Only Manager’s perpetual nature even gives the possibility (however difficult) of adding historical information.
The time investment comes in setting up your chart of accounts, enabling the desired functional tabs, setting defaults, importing tax codes and other localizations, and so forth. You will have to do that regardless. The nice thing about Manager is that you can do all those things as you need them, whereas most programs require it all to be set up in advance, before entering the first transaction.
Realistically, what you gain by having all that historical data is the ability to search for past transactions. Even very large companies with customized accounting systems often give that up when migrating systems. It is just too expensive to convert all the data to the new structure.