This is just my own personal opinion but I will not be spending an additional $500+ on an aftermarket mod manufactured by Stern for a game that costs at least $5100.
The math just doesn't make sense. It's not like you miss them being there with the game as it is. And unless they do something amazing, like work with the magnets to hold and move the balls while captured by the streams, I just can't fathom spending the cash on them.
Hell, add another $1500 and get another DMD game FTW....
Stern's greed is getting in the way of them making mods that are affordable enough for them to be attractive IMHO.