Seeing as the Blooming itself consumes quite the number of gold coins, I find the option to save some rather nice.
Also the leveling up feels "faster" to me when its done with the L20 manyus once, instead of twice/thrice with the L5 ones. This is especially true the higher you climb on the current LVL.
Plus the option to make extra space when necessary is also quity handy.
Overall its a good function and I think many people would find it worthwhile, since I know for sure there are some guys here who are hardcore Inventory shuffle mages, unwilling to increase their space, thus having to play that Diablo-esque Inventory Tetris all the time