I have a MD MKII no UW since 2009. Last year, i sold it and buy a MKII UW + and i find it important to have the +Drive.
I think it’s necessary if your MD is a tool you really use a lot and, more of all, if you like to create different sounds and things like sound design.
Because i don’t have DAW, the internal memory is fondamental. Before the +, i had to make chooses between the sounds i created, in view to create other ones, there was no place to store new sounds. This way i lost a lot of sounds i regret now.
You can arg that if i really now the MD i can recreate them…yes, indeed, but really, there is a difference now, it is more confortable.