Flexible casting revisions
Creating spell slots is the only thing that is kept from flexible casting. As stated above, downcasting is done as part of the action the spell uses. The same is true for creating spell slots. Converting sorcery points to spell slots is part of the action used to cast the spell. I think that this saves time and fits with the story of them harnessing the magic that is in them to create these effects.
The sorcery points required for spell slots stay the same.
You may be thinking, what happens if you multiclass with these rules? Multiclassing should not be a problem. Since downcasting is a more streamlined version of the flexible casting rules, you can multiclass as you would a regular sorcerer.
Using this rule, the spell sot to sorcery point conversion is more forgiving. Before, if you turned a 5th level slot into points, you would not be able to cast a 4th level spell. With this, however, you can. This definitely gives your sorcerer more flexibility, which I believe will make for a more fun experience.